On average the acorn weighs... (given 4 weights) THANK YOU IN ADVANCE

Question

You are given 4 acorn weights (in grams): 3.0, 3.0, 3.5, and 2.5

On average the acorn weighs...

A) 3.0 plus or minus 0g

B) 3.0 plus or minus 0.25g

C) 3.0 plus or minus 0.50g

 

Please explain! It seems as though A) is the obvious answer but I feel like there's some sort of trick with the plus/minus thing. Thank you so much!

Answer 1

 

∑X=3.0+3.0+3.5+2.5=12.0

n=4 (since they are 4 acorn)

 

average = mean = ∑X/n = 12.0/4=3.0

 

The range of the weights is + or - 0.5g from the mean

 

the answer is choice C and this is the trick