The weight of some group of people has normal distribution w

The weight of some group of people has normal distribution

with a mean of 200 pounds and a standard deviation of 25 pounds.

Find the probability that a randomly selected person in this group

has a weight less than 180 pounds, P(x < 180) ?

0.2119

0.3915

0.4378

0.0195

Solution

Given that the distribution is normal, we find the Z--score

Z = X - mean / SD

= 180 - 200 / 25

= -20 / 25

= -0.8

P(X<180) = P(Z < -0.8)

Looking at the normal distribution table,

P(Z<-0.8) = 0.21186

~ 0.2119

Thus, option A is correct. Hope this helps,