The weights of bats in a zoo are normally distributed with a mean of 2.2 pounds and a standard deviation of 0.3 pounds. about what percent of the bats at the zoo weigh between 1.9 pounds and 2.5 pounds?

a. 34%

b. 47.5%

c. 81.5%

d. 68%

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.
D ) 68 %

The weights of bats in a zoo are normally distributed with a mean of 2.2 pounds and a standard deviation of 0.3 pounds. About what percent of the bats at the zoo weigh between 1.9 pounds and 2.5 pounds?

Out of all the answer shown above the one that best represents the percentage of the bats at the zoo that weight between 1.9 pounds and 2.5 pounds is answer choice D) 68%. The reason being that both points are exactly 1 standard deviation of the mean.

I hope it helps, Regards.

Subtracting is the opposite of adding