Question

The scores on the Wechsler Intelligence Scale for Children (WISC) are thought to be Normally distributed with a standard deviation of 10.

A simple random sample of 25 children is taken, and each is given the WISC.
The mean of the 25 scores is 104.32.

Based on these data, what is a 95% confidence interval for true mean score?

Answer 1

Answer: Interval would be (100.4,108.24).

Explanation:

Since we have given that

Standard deviation = 10

Mean = 104.32

N = 25

We need to find 95% confidence interval.

At 95% confidence interval, z = 2.58

So, interval would be

`\bar{x}\pm z(\sigma)/(√(n))\\\\=104.32\pm 1.96* (10)/(√(25))\\\\=104.32\pm (19.6)/(5)\\\\=104.32\pm 3.92\\\\=(104.32-3.92,104.32+3.92)\\\\=(100.4,108.24)`

Hence, interval would be (100.4,108.24).