Problem Set: Ratios, Rates, Probabilities, and Averages
Calculate the Mean of a Set of Numbers
In the following exercises, find the mean.- , , , ,
Answer: 4
- , , , , ,
- , , , , ,
Answer: 35
- , , , , and
- , , ,
Answer: 245.5
- , , ,
- , , , , ,
Answer: 11.65
- , , , , , , ,
- {$270} , {$310.50} , {$243.75} , and {$252.15}
Answer: $269.10
- Each workday last week, Yoshie kept track of the number of minutes she had to wait for the bus. She waited minutes. Find the mean
- In the last three months, Raul’s water bills were {$31.45}, {$48.76},\text{and} {$42.60}. Find the mean.
Answer: $40.94
Calculate the Mean of a Set of Numbers in Applications
In the following exercises, find the mean.- Four girls leaving a mall were asked how much money they had just spent. The amounts were {$0} , {$14.95} , {$35.25} , and {$25.16} . Find the mean amount of money spent.
Answer: $18.84
- Juan bought shirts to wear to his new job. The costs of the shirts were {$32.95} , {$38.50} , {$30.00} , {$17.45} , and {$24.25} . Find the mean cost.
- The number of minutes it took Jim to ride his bike to school for each of the past six days was , , , , , and . Find the mean number of minutes.
Answer: 19.5 minutes
- Norris bought six books for his classes this semester. The costs of the books were {$74.28} , {$120.95} , {$52.40} , {$10.59} , {$35.89} , and {$59.24} . Find the mean cost.
- The top eight hitters in a softball league have batting averages of , , , , , , , and . Find the mean of the batting averages. Round your answer to the nearest thousandth.
Answer: 0.329
- The monthly snowfall at a ski resort over a six-month period was , , , , , and inches. Find the mean snowfall.
Find the Median of a Set of Numbers
In the following exercises, find the median.- , , , ,
Answer: 21
- , , , ,
- , , , , , , , ,
Answer: 45
- , , , , , , , ,
- , , , , , , ,
Answer: 4.5
- , , , , , , ,
- , , , , ,
Answer: 99.65
- , , , , , , ,
- , , , ,
- , , , , , , ,
Answer: 24.5
Find the Median of a Set of Numbers in Applications
In the following exercises, find the median.- Last week Ray recorded how much he spent for lunch each workday. He spent {$6.50} , {$7.25} , {$4.90} , {$5.30} , and {$12.00} . Find the median.
Answer: $6.50
- Michaela is in charge of 6 two-year olds at a daycare center. Their ages, in months, are , , , , , and . Find the median age.
- Brian is teaching a swim class for three-year olds. Their ages, in months, are . Find the median age.
Answer: 40.5 months
- Sal recorded the amount he spent for gas each week for the past weeks. The amounts were {$38.65}, {$32.18}, {$40.23}, {$51.50}, {$43.68}, {$30.96}, {$41.37}, and {$44.72}. Find the median amount.
- The ages of the eight men in Jerry’s model train club are . Find the median age.
- The number of clients at Miranda’s beauty salon each weekday last week were . Find the median number of clients.
Answer: 16 clients
Identify the Mode of a Set of Numbers
In the following exercises, identify the mode.- , , , , , , , , , ,
Answer: 2
- , , , , , , , , , ,
- , , , , , , , , , , , , , , , , , , ,
Answer: 22
- , , , , , , , , , , , , , , , , , , , ,
- The number of children per house on one block: , , , , , , , , , , , , .
Answer: 2 children
- The number of movies watched each month last year: , , , , , , , , , , , .
- The number of units being taken by students in one class: , , , , , , , , , , , .
Answer: 11 units
- The number of hours of sleep per night for the past two weeks: , , , , ,
- , , , , , , , , .
- , , , , , , , ,
- The number of siblings of a group of students: , , , , , , , , , , ,
Answer: 2
Use the Basic Definition of Probability
In the following exercises, express the probability as both a fraction and a decimal. (Round to three decimal places, if necessary.)- Josue is in a book club with members. One member is chosen at random each month to select the next month’s book. Find the probability that Josue will be chosen next month.
Answer:
- Jessica is one of eight kindergarten teachers at Mandela Elementary School. One of the kindergarten teachers will be selected at random to attend a summer workshop. Find the probability that Jessica will be selected.
- There are people who work in Dane’s department. Next week, one person will be selected at random to bring in doughnuts. Find the probability that Dane will be selected. Round your answer to the nearest thousandth.
Answer:
- Monica has two strawberry yogurts and six banana yogurts in her refrigerator. She will choose one yogurt at random to take to work. Find the probability Monica will choose a strawberry yogurt.
- Michel has four rock CDs and six country CDs in his car. He will pick one CD to play on his way to work. Find the probability Michel will pick a rock CD.
Answer:
- Noah is planning his summer camping trip. He can’t decide among six campgrounds at the beach and twelve campgrounds in the mountains, so he will choose one campground at random. Find the probability that Noah will choose a campground at the beach.
- Donovan is considering transferring to a . He is considering out-of state colleges and colleges in his state. He will choose one college at random to visit during spring break. Find the probability that Donovan will choose an out-of-state college.
Answer:
- There are number combinations possible in the Mega Millions lottery. One winning jackpot ticket will be chosen at random. Brent chooses his favorite number combination and buys one ticket. Find the probability Brent will win the jackpot. Round the decimal to the first digit that is not zero, then write the name of the decimal.
- The Sustainability Club sells tickets to a raffle, and Albert buys one ticket. One ticket will be selected at random to win the grand prize. Find the probability Albert will win the grand prize. Express your answer as a fraction and as a decimal.
- Luc has to read novels and short stories for his literature class. The professor will choose one reading at random for the final exam. Find the probability that the professor will choose a novel for the final exam. Express your answer as a fraction and as a decimal.
Everyday Math
- Joaquin gets paid every Friday. His paychecks for the past Fridays were {$315}, {$236.25}, {$236.25}, {$236.25}, {$315}, {$315}, {$236.25}, {$393.75}. Find the ⓐ mean, ⓑ median, and ⓒ mode.
Answer: ⓐ $285.47 ⓑ $275.63 ⓒ $236.25
- The cash register receipts each day last week at a coffee shop were {$1,845}, {$1,520}, {$1,438}, {$1,682}, {$1,850}, {$2,721}, {$2,539}. Find the ⓐ mean, ⓑ median, and ⓒ mode.
Writing Exercises
Explain in your own words the difference between the mean, median, and mode of a set of numbers. [practice-area rows="4"][/practice-area] Make an example of probability that relates to your life. Write your answer as a fraction and explain what the numerator and denominator represent. [practice-area rows="4"][/practice-area]Write a Ratio as a Fraction
In the following exercises, write each ratio as a fraction.- to
Answer:
- to
- to
Answer:
- to
- to
Answer:
- to
- to
Answer:
- to
- to
Answer:
- to
- to
Answer:
- to
- to
Answer:
- to
- {$18} to {$63}
Answer:
- {$16} to {$72}
- {$1.21} to {$0.44}
Answer:
- {$1.38} to {$0.69}
- ounces to ounces
Answer:
- ounces to ounces
- feet to feet
Answer:
- feet to feet
- milligrams to milligrams
Answer:
- milligrams to milligrams
- total cholesterol of to HDL cholesterol of
Answer:
- total cholesterol of to HDL cholesterol of
- inches to foot
Answer:
- inches to foot
- to to
Answer:
- to
- to
Answer:
-
Answer:
- ounces to ounces
- inches to feet
Answer:
Write a Rate as a Fraction
In the following exercises, write each rate as a fraction.- calories per ounces
Answer:
- calories per ounces
- pounds per square inches
Answer:
- pounds per square inches
- miles in hours
Answer:
- miles in hours
- {$595} for hours
Answer: \Large\frac{{$119}}{{8 hours}}
- {$798} for hours
- calories per ounces
- pounds per square inches
Answer:
- miles in hours
- {$612.50} for hours
Answer: \Large\frac{$612.50}{35\text{hours}}
Find Unit Rates
Exercise 1
In the following exercises, find the unit rate. Round to two decimal places, if necessary.-
- calories per ounces
Answer: 11.67 calories/ounce
- calories per ounces
- pounds per square inches
Answer: 2.73 lbs./sq. in.
- pounds per square inches
- miles in hours
Answer: 69.71 mph
- miles in hours
- {$595} for hours
Answer: $14.88/hour
- {$798} for hours
- miles on gallons of gas
Answer: 32 mpg
- miles on gallons of gas
- pounds in weeks
Answer: 2.69 lbs./week
- pounds in weeks
- beats in minute
Answer: 92 beats/minute
- beats in minute
- calories per ounces
- pounds per square inches
Answer: 12 pounds/sq.in.
- miles in hours
- {$612.50} for hours
Answer: $17.50/hour
- calories per ounces
Exercise 2
-
- The bindery at a printing plant assembles magazines in hours. How many magazines are assembled in one hour?
Answer: 8,000
- The pressroom at a printing plant prints sections in hours. How many sections are printed per hour?
- The bindery at a printing plant assembles magazines in hours. How many magazines are assembled in one hour?
Find Unit Price
Exercise 1
In the following exercises, find the unit price. Round to the nearest cent.-
- Soap bars at for {$8.69}
Answer: $1.09/bar
- Soap bars at for {$3.39}
- Women’s sports socks at pairs for {$7.99}
Answer: $1.33/pair
- Men’s dress socks at pairs for {$8.49}
- Snack packs of cookies at for {$5.79}
Answer: $0.48/pack
- Granola bars at for {$3.69}
- CD-RW discs at for {$14.99}
Answer: $0.60/disc
- CDs at for {$4.49}
- t-shirts: for {$8.97}
- Highlighters: for {$2.52}
Answer: $0.42
- An office supply store sells a box of pens for {$11}. The box contains pens. How much does each pen cost?
- Anna bought a pack of kitchen towels for {$13.20}. How much did each towel cost? Round to the nearest cent if necessary.
Answer: $1.65
- Soap bars at for {$8.69}
Exercise 2
-
- The grocery store has a special on macaroni and cheese. The price is {$3.87} for boxes. How much does each box cost?
Answer: $1.29/box
- The pet store has a special on cat food. The price is {$4.32} for cans. How much does each can cost?
- The grocery store has a special on macaroni and cheese. The price is {$3.87} for boxes. How much does each box cost?
Exercise 3
In the following exercises, find each unit price and then identify the better buy. Round to three decimal places.-
- Mouthwash, size for {$6.99} or size for {$4.79}
Answer: The 50.7-ounce size costs $0.138 per ounce. The 33.8-ounce size costs $0.142 per ounce. The 50.7-ounce size is the better buy.
- Toothpaste, ounce size for {$3.19} or size for {$5.19}
- Breakfast cereal, ounces for {$3.99} or ounces for {$3.29}
Answer: The 18-ounce size costs $0.222 per ounce. The 14-ounce size costs $0.235 per ounce. The 18-ounce size is a better buy.
- Breakfast Cereal, ounces for {$2.69} or ounces for {$3.69}
- Ketchup, regular bottle for {$2.99} or squeeze bottle for {$4.39}
Answer: The regular bottle costs $0.075 per ounce. The squeeze bottle costs $0.069 per ounce. The squeeze bottle is a better buy.
- Mayonnaise regular bottle for {$3.49} or squeeze bottle for {$4.99}
- Cheese {$6.49} for lb. block or {$3.39} for lb. block
Answer: The half-pound block costs $6.78/lb, so the 1-lb. block is a better buy.
- Candy {$10.99} for a lb. bag or {$2.89} for lb. of loose candy
- Shampoo: ounces for {$4.29} or ounces for {$7.29}?
- Vitamins: tablets for {$6.49} or for {$11.99}?
Answer: $0.11, $0.12; 60 tablets for $6.49
- Mouthwash, size for {$6.99} or size for {$4.79}
Translate Phrases to Expressions with Fractions
In the following exercises, translate the English phrase into an algebraic expression.-
- miles per hours
Answer:
- feet per seconds
- {$3} for lbs.
Answer: \Large\frac{{$3}}{{0.5 lbs}.}
- beats in minutes
- calories in ounces
Answer:
- minutes for dollars
- the ratio of and
Answer:
- the ratio of and
- miles per
- adults to children
Answer:
- the ratio of and the difference of and
- the ratio of and the sum of and
Answer:
- miles per hours
Everyday Math
Everyday math
- One elementary school in Ohio has students and teachers. Write the student-to-teacher ratio as a unit rate.
Answer: 15.2 students per teacher
- The average American produces about pounds of paper trash per year (365 days). How many pounds of paper trash does the average American produce each day? (Round to the nearest tenth of a pound.)
- A popular fast food burger weighs ounces and contains calories, grams of fat, grams of carbohydrates, and grams of protein. Find the unit rate of ⓐ calories per ounce ⓑ grams of fat per ounce ⓒ grams of carbohydrates per ounce ⓓ grams of protein per ounce. Round to two decimal places.
Answer: ⓐ 72 calories/ounce ⓑ 3.87 grams of fat/ounce ⓒ 5.73 grams carbs/once ⓓ 3.33 grams protein/ounce
- A chocolate mocha coffee with whipped cream contains calories, grams of fat, grams of carbohydrates, and grams of protein. Find the unit rate of ⓐ calories per ounce ⓑ grams of fat per ounce ⓒ grams of carbohydrates per ounce ⓓ grams of protein per ounce.
Writing Exercises
- Would you prefer the ratio of your income to your friend’s income to be or Explain your reasoning. Answers will vary.
- The parking lot at the airport charges {$0.75} for every minutes. ⓐ How much does it cost to park for hour? ⓑ Explain how you got your answer to part ⓐ. Was your reasoning based on the unit cost or did you use another method?
- Kathryn ate a cup of frozen yogurt and then went for a swim. The frozen yogurt had calories. Swimming burns calories per hour. For how many minutes should Kathryn swim to burn off the calories in the frozen yogurt? Explain your reasoning. Answers will vary.
- Mollie had a cappuccino at her neighborhood coffee shop. The cappuccino had calories. If Mollie walks for one hour, she burns calories. For how many minutes must Mollie walk to burn off the calories in the cappuccino? Explain your reasoning.
-
-
Answer: 6
-
Answer: 8
-
Answer: −2
-
Answer: −1
-
Answer: not a real number
-
Answer: not a real number
-
Answer: 5
-
Answer: 7
-
Answer: 12
-
Answer: −9
-
Answer: not a real number
-
Answer: 17
-
Estimate Square Roots
In the following exercises, estimate each square root between two consecutive whole numbers.-
-
Answer:
-
Answer:
-
Answer:
-
Approximate Square Roots with a Calculator
In the following exercises, use a calculator to approximate each square root and round to two decimal places.-
-
Answer: 4.36
-
Answer: 7.28
-
Answer: 7.55
-
Simplify Variable Expressions with Square Roots
In the following exercises, simplify. (Assume all variables are greater than or equal to zero.)-
-
Answer: y
-
Answer: 7x
-
Answer: −8a
-
Answer: 12xy
-
Answer: 8b
-
Answer: 15mn
-
Answer: 7y
-
Answer: 11cd
-
Use Square Roots in Applications
In the following exercises, solve. Round to one decimal place. Landscaping Reed wants to have a square garden plot in his backyard. He has enough compost to cover an area of square feet. How long can a side of his garden be?-
Answer: 8.7 feet
-
Answer: 8 seconds
-
Answer: 15.8 seconds
-
Answer: 72 mph
-
Answer: 53.0 mph
-
Everyday Math
- Decorating Denise wants to install a square accent of designer tiles in her new shower. She can afford to buy square centimeters of the designer tiles. How long can a side of the accent be?Decorating Morris wants to have a square mosaic inlaid in his new patio. His budget allows for tiles. Each tile is square with an area of one square inch. How long can a side of the mosaic be?
Answer: 45 inches
Writing exercises
- Why is there no real number equal to
- What is the difference between and Answers will vary. 92 reads: "nine squared" and means nine times itself. The expression reads: "the square root of nine" which gives us the number such that if it were multiplied by itself would give you the number inside of the square root.
- Decorating Denise wants to install a square accent of designer tiles in her new shower. She can afford to buy square centimeters of the designer tiles. How long can a side of the accent be?Decorating Morris wants to have a square mosaic inlaid in his new patio. His budget allows for tiles. Each tile is square with an area of one square inch. How long can a side of the mosaic be?