Answer:
The option D) 1.50 is correct
That is the standard error of the sample mean is 1.50
Explanation:
Given that a population that consists of 500 observations has a mean of 40 and a standard deviation of 15.
A sample size is 100 taken at random from the given population.
To find the standard error of the sample mean :
From the given Mean=40 and

For N=100
The formula for standard error is

Substitute the values in the above formula we get



∴

∴ The standard error of the sample mean is 1.50
Hence the option D) 1.50 is correct