The 95% on the z-table is 1.96.
Now find the standard error of the mean by dividing standard deviation by the square root of the sample:
2 / √64 = 0.25
Multiply the standard error by the z-table :
0.25 x 1.96 = 0.49
Now add and subtract that from the mean:
27.5 - 0.49 = 27.01 = 27
27.5 +0.49 = 27.99 = 28
The answer is: 27 ≤ u ≤ 28
