That are 8 of 1600 people
:8
-->8/1600 --> 1/200 --> 0,5/100 --> 0,5 %
Answer: (36.7, 39.3)
Step-by-step explanation:
Confidence interval for population mean:
, where n= sample size,
= sample mean,
= population standard deviation,
= critical z value.
Given: n= 40 , 
Critical z-value for 90% confidence = 1.645
Then, required confidence interval:

Hence, a 90% Confidence Interval = (36.7, 39.3)
A is the correct answer because if you add any of it's 2 numbers it is always greater than it's 3rd number
It’s 12 units long I
Hope it the answer just trying to help