Question

According to a survey, high school girls average 100 text messages daily. Assume the population standard deviation is 20 text messages. Suppose a random sample of 50 high school girls is taken.

What is the standard deviation of mean daily text messages based on the sample of 50 high school girls?
Please provide an answer with 2 decimal point.

Answer 1

Given that,

Daily average text messages by high school girls =

Assume that population standard deviation is

number of random sample of high school girls =50

Here we have to find standard deviation of mean daily text messages based on sample of 50 high school girls.

Here sample size =n=50 > 30

So according central limit theorem,

Mean daily text messages =  

Where ,

and

So standard deviation for mean daily text messages is 2.828427=2.83( rounded to 3 decimal)