Question

An educational psychologist wishes to know the mean number of words a third grader can read per minute. She wants to make an estimate at the 95% level of confidence. For a sample of 1674 third graders, the mean words per minute read was 29. Assume a population standard deviation of 5.4. Construct the confidence interval for the mean number of words a third grader can read per minute. Round your answers to one decimal place

Answer 1

Solution :

Given that,

Sample size = n = 1674

Z/2 = 1.96

Margin of error = E = Z/2* ( /n)

= 1.96 * (5.4 / 1674)

Margin of error = E = 0.3

At 95% confidence interval estimate of the population mean is,

- E < < + E

29 - 0.3 < < 29 + 0.3

28.7 < < 29.3

(28.7 , 29.3)