PEMDAS
We start with exponents.
4 x 4 is 16
12 divided by 3 is 4
4 times 5 is 20
20-16 is 4
4 is the answer.
Mean : m = 2.2
Standard deviation: s = 0.3
m - 1 s = 2.2 - 0.3 = 1.9
m + 1 s = 2.2 + 0.3 = 2.5
For the normal distribution the values less than 1 standard deviation away from the mean account for 68.27 % of the set.
Answer: D ) 68 %
You are looking for the circumference. which is C(circumference)=

x r (radius)
the radius is =to half of the diameter.
c=56.55