Let

denote the random variable representing a given number in the total set of numbers. We're told that

of the numbers fall within a given range, so we know

where

is normally distributed with mean 45 and an unknown variance

.
Let's make the transformation to a random variable with a standard normal distribution:

Since

is symmetric, we have

The mean of

is 0, and by symmetry we know that exactly half of the distribution falls to the left of

, so

. We're left with


This probability corresponds to a value of

, which means
Answer:
See below.
Step-by-step explanation:
1.
5^2 + 12^2 = x^2
25 + 144 = x^2
169 = x^2
x = 13
2.
3^2 + x^2 = [sqrt(10)]^2
9 + x^2 = 10
x^2 = 1
x = 1
3.
1^2 + x^2 = 4^2
1 + x^2 = 16
x^2 = 15
x = sqrt(15)
4.
[sqrt(27)]^2 + x^2 = 6^2
27 + x^2 = 36
x^2 = 9
x = 3
5.
15/5 = c/sqrt(29)
5c = 15 * sqrt(29)
c = 3sqrt(29)
6.
26/13 = x/12
2 = x/12
x = 24
3.14 * 18=56.52
so your answer is c
hope i helped
good luck on your homework