Answer:
1.5
Step-by-step explanation:
The mean is the Middle number.
1 standard deviation in both sides of 7.5 makes it between 6 and 9.
<u>What is the </u><u>"common difference"</u><u> in 6 to 7.5 and from 7.5 to 9?</u>

and

So, we would say the standard deviation is 1.5
Answer choice A is right.
Answer:
Height
Step-by-step explanation:
The answer is C. Greenwich,England.
The answer is, 4 + 8 + 12 + 16 ... rule is 4n.
Explanation:
one square has 4 toothpicks, then you added 4 picks (because you started with zero squares).
4 squares have 12 toothpicks, then you added 8 toothpicks to pass from one square to 4 squeres.
If you follow that reasoing you get to realize that the additions are 4, 8, 12, 16.