Chapter 11.5, Problem 5E

a.

To determine

To calculate:

Population proportion $\left(p\right)$ of teen cell phone users.

Answer to Problem 5E

Population proportion $\left(p\right)$ of teen cell phone users is $0.267$ .

Explanation of Solution

Given information:

Cell phone users send more than $70$ text.

Calculation:

Population mean is calculated as,

  $p=\frac{X}{N}$

Where,

  $p=$ Population proportion.

  $X=$ number of successes.

  $N=$ sample size.

Count the amount over $70$ and put it over total. Total given is $30$

Substitute the values in above equation,

  $\begin{array}{l}p=\frac{X}{N}\\ p=\frac{8}{30}\\ p=0.2666\end{array}$

Hence, Population proportion $\left(p\right)$ of teen cell phone users is $0.2666$ .

b.

To determine

To calculate:

Population proportion $\left(p\right)$ of teen cell phone users.

Answer to Problem 5E

Population proportion $\left(p\right)$ of teen cell phone users is $0.267$ .

Explanation of Solution

Given information:

Cell phone users send fewer than $50$ text.

Calculation:

Population mean is calculated as,

  $p=\frac{X}{N}$

Where,

  $p=$ Population proportion.

  $X=$ number of successes.

  $N=$ sample size.

Count the amount under $50$ and also over $30$ .

Substitute the values in above equation,

  $\begin{array}{l}p=\frac{X}{N}\\ p=\frac{8}{30}\\ p=0.2666\end{array}$

Hence, Population proportion $\left(p\right)$ of teen cell phone users is $0.2666$ .