Let x1, x2, be a random sample from a distribution with mean 64 and standard deviation 4. then mean and the standard deviation of the sample mean are:

The mean of sample means is the same as the mean of the underlying distribution.

The standard deviation of sample means is the original distribution sample mean divided by the square root of the number of samples.

Mean of sample mean distribution: 64

SD of sample mean distribution: 4/√64 = 1/2

y= 2x+7

changed to y= 5x +7

as slope is increased from 2 to 5

therefore it would be less steeper

so, option d) is correct