Question

A sample of scores has EX = 40 and a mean of 4. The size of the sample must be

a) 3
b) 4
c) 5
d) 10
e) 45

Answer 1

The sample size cannot be determined from the given information.

Step-by-step explanation:

The sample size can be determined by using the formula:

n = (Z * s / E)^2

Where n is the sample size, Z is the Z-score corresponding to the desired confidence level (e.g., for a 95% confidence level, Z = 1.96), s is the standard deviation of the population, and E is the desired margin of error.

In this case, the population mean (EX) is 40 and the mean is 4. Since the sample mean is the same as the population mean, the margin of error (E) is 0. Therefore, the formula becomes:

n = (Z * s / 0)^2

A denominator of 0 is undefined, so the sample size cannot be determined from the given information. Therefore, none of the answer options (a, b, c, d, e) are correct.