Lesson 13

Median

Problem 1

Here is data that shows a student's scores for 10 rounds of a video game.

130

150

120

170

130

120

160

160

190

140

What is the median score?

A:

125

B:

145

C:

147

D:

150

Solution

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Problem 2

When he sorts the class’s scores on the last test, the teacher notices that exactly 12 students scored better than Clare and exactly 12 students scored worse than Clare. Does this mean that Clare’s score on the test is the median? Explain your reasoning.

Solution

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Problem 3

The medians of the following dot plots are 6, 12, 13, and 15, but not in that order. Match each dot plot with its median.

Four dot plots, 0 to 20 by twos.

Solution

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Problem 4

Invent a data set with five numbers that has a mean of 10 and a median of 12.

Solution

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Problem 5

Ten sixth-grade students reported the hours of sleep they get on nights before a school day. Their responses are recorded in the dot plot.

A dot plot, hours of sleep, 5 to 12 by ones.  Beginning at 5, the number of dots above each increment is 1, 1, 3, 3, 2, 0, 0, 0.

Looking at the dot plot, Lin estimated the mean number of hours of sleep to be 8.5 hours. Noah's estimate was 7.5 hours. Diego's estimate was 6.5 hours.

Which estimate do you think is best? Explain how you know.

Solution

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(From Unit 8, Lesson 10.)

Problem 6

In one study of wild bears, researchers measured the weights, in pounds, of 143 wild bears that ranged in age from newborn to 15 years old. The data were used to make this histogram.

  1. What can you say about the heaviest bear in this group?
  2. What is a typical weight for the bears in this group?
  3. Do more than half of the bears in this group weigh less than 250 pounds?
  4. If weight is related to age, with older bears tending to have greater body weights, would you say that there were more old bears or more young bears in the group? Explain your reasoning.
A histogram, weight in pounds, from 0 to 550 by fifties. Beginning at zero up to but not including 50, height of bar at each interval is 6, 18, 40, 28, 14, 7, 11, 10, 8, 2, 1.

Solution

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(From Unit 8, Lesson 8.)