Question

The graph shows the distribution of the number of text messages young adults send per day. The distribution is approximately Normal, with a mean of 128 messages and a standard deviation of 30 messages.
A graph titled daily text messaging has number of text on the x-axis, going from 8 to 248 in increments of 30. Data is distributed normally. The highest point of the curve is at 128.

What percentage of young adults send between 128 and 158 text messages per day?
34%
50%
66%
68%

Answer 1

The percentage of young adults send between 128 and 158 text messages per day is; 34%

How to find the percentage from z-score?

The distribution is approximately Normal, with a mean of 128 messages and a standard deviation of 30 messages.

We are given;

Sample mean; x' = 158

Population mean; μ = 128

standard deviation; σ = 30

We want to find the area under the curve from x = 248 to x = 158.

where x is the number of text messages sent per day.

To find P(158 < x < 248), we will convert the score x = 158 to its corresponding z score as;

z = (x - μ)/σ

z = (158 - 128)/30

z = 30/30

z = 1

This tells us that the score x = 158 is exactly one standard deviation above the mean μ = 128.

From online p-value from z-score calculator, we have;

P-value = 0.34134 = 34%

Approximately 34% of the the population sends between 128 and 158 text messages per day.

Read more about p-value from z-score at; brainly.com/question/25638875

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