Question

The scores of individual students on the American College Testing (ACT) Program composite college entrance examination have a Normal distribution with mean that varies slightly from year to year and standard deviation 6.0. You plan to take an SRS of size n of the students who took the ACT exam this year and compute the mean score of the students in your sample. You will use this to estimate the mean score of all students this year. In order for the standard deviation of to be no more than 0.1, how large should n be

Answer 1

The sample size must be atleast 3600

Explanation:

We are given the following in the question:

The scores of individual students on the American College Testing (ACT) Program is a bell shaped distribution that is a normal distribution.

Population standard deviation = 6.0

We want that the sample standard deviation should not be more than 0.1.

Thus, the standard error should not be more than 0.1.

Standard error =

`=(\sigma)/(√(n))`

Putting values, we get,

`(\sigma)/(√(n))\leq 0.1\\\\ (6)/(√(n)) \leq 0.1\\\\ √(n)\geq 60\\n\geq 3600`

Thus, the sample size must be atleast 3600