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Don鈥檛 call me According to a study by Nielsen Mobile, 鈥淭eenagers ages 13 to 17 are by far the most prolific texters, sending 1742 messages a month.鈥 Mr. Williams, a high school statistics teacher, was skeptical about the claims in the article. So he collected data from his first-period statistics class on the number of text messages they had sent over the past 24 hours. Here are the data:

a. Sunny was the student who sent 42 text messages. What is Sunny鈥檚 percentile?

b. Find the number of text messages sent by Joelle, who is at the 16th percentile of the distribution.

Short Answer

Expert verified

Part (a) Percentile that corresponds to 42 text messages is 72nd percentile.

Part (b) Joelle sent only 1 text message.

Step by step solution

01

Part (a) Step 1: Given information

Data values:

071292585125989026
81187209252143344542
02

Part (a) Step 2: Concept

The percentile of an individual is the percentage of the distribution that is less than the data value of the individual.

03

Part (a) Step 3: Calculation

Let

n,the number of data values that are fewer than the data value of a single individual.

N,Total number of data values

Now,

Sort the values of all the data in ascending order:

0,0,0,1,1,3,3,5,5,7,8,8,9,14,25,25,26,29,42,44,52,72,92,98,118

Note that

18of the 25data values are smaller than 42

The percentile of an individual is the percentage of the distribution that is less than the data value of the individual.

Percentile=nN100%=100%1825=0.72100%=72%

Thus,

The percentile that corresponds with 42text messages is the 72ndpercentile.

04

Part (b) Step 1: Calculation

Let

n, the number of data values that are fewer than the data value of a single individual.

N, Total number of data values

Now,

Sort all the data values in ascending order:

0,0,0,1,1,3,3,5,5,7,8,8,9,14,25,25,26,29,42,44,52,72,92,98,118

Note that

The data set consists of 25 data values.

Such that

N=25

The data value represented by the xth percentile has x% of the data values below it.

Then

16th percentile has 16% of the 25 data values below it.

Calculate 16% of 25 data values:

n=16%N=1610025=42525=4

We have

4 out of 25 data values are smaller than 16th percentile.

16th percentile needs to be the 5th data value in the ascending order, and that is 1

Thus,

The 16th percentile is 1 text message.

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