Lesson 18: Practice Problems

Problem 1

Twenty students timed how long each of them took to solve a puzzle. Here is a dot plot of their solution times.

Dot plot for “puzzle-solving time in minutes.” The numbers 0 through 14, in increments of 2, are indicated. The data are as follows: 2 minutes, 1 dot; 6 mintues, 1 dot; 7 minutes, 2 dots; 8 minutes, 3 dots; 9 minutes, 7 dots; 10 minutes; 2 dots; 11 minutes; 3 dots; 12 minutes; 1 dot.

Predict which measure of center —the mean or the median—will be larger. Explain your reasoning.
Calculate the mean and the median. Was your prediction correct?
Which pair of measures of center and variability—mean and MAD, or median and IQR—would you choose to describe the distribution of the solution times? Explain your reasoning.

Problem 2

A local library showed a movie during a children’s festival. Jada recorded the ages of 100 children who watched the movie. Here is a histogram for her data.

A histogram: The horizontal axis is labeled "age in years" and the numbers 1 through 10 are indicated. On the vertical axis the numbers 0 through 50, in increments of 10, are indicated. The data represented by the bars are as follows: Age from 1 up to 3, 10. Age from 3 up to 5, 25. Age from 5 up to 7, 50. Age from 7 up to 9, 15.

Answer each question. Explain your reasoning for each answer.

Can the histogram be used to estimate the mean age of the movie watchers?
Can the histogram be used to estimate the median age of the movie watchers?
Can the histogram be used to find the exact median age of the movie watchers?
Is it possible to tell from the histogram if there was at least one 3-year-old who watched the movie?

Problem 3 From Unit 8 Lesson 5

In a game, players are shown a picture that has 14 butterfly shapes hidden in it. They are given 3 minutes to find as many hidden butterfly shapes as they can.

Twenty fourth-grade students and twenty sixth-grade students played this game. The dot plots represent the numbers of butterfly shapes the two groups found.

Two dots plots showing number of butterflies found for fourth-grade and sixth-grade.

Write a few sentences comparing the numbers of hidden butterflies found for these two groups of students.

Problem 4 From Unit 8 Lesson 15

In a round of mini-golf, Elena records the number of strokes it takes to hit the ball in the hole for each green. Find the range, median, and interquartile range for the number of strokes needed on each green.