If 1.25% of the area lies to the left of 42, and 1.25% right to the right of 48, what is the mean and standard deviation of the normal distribution?

1 Answer
Mar 26, 2018

The mean is 45 and the standard deviation is 1.34.

Explanation:

In a normal distribution, if #p= 0.0125#, then #z=2.2414#. Since the normal distribution is symmetric, the mean will be the average of the two limits, namely #(48+42)/2=45#.

#z=(x-mu)/sigma=2.2414=(48-45)/sigma#

where #sigma# is the standard deviation. Solving for #sigma# we have

#sigma=(48-45)/2.2414=1.34#