Answer: A. 1.2
Step-by-step explanation:
Given : Sample size : n= 64
Standard deviation: 
The formula to find the standard error of mean is given by :-

Therefore, the standard error of the mean= 1.2
Hence, A is the right option.
Answer:
The fantastic four in 1961
Step-by-step explanation:
Circumference (C):

Area (A):

I thought doubling everytime except for the number 19000 because if you do 250 × 2 = 500 so then you do 500×2=1000.