Question

Brain weights are normally distibuted with mean 1400.48 grams and standard deviation 106.33 grams. Find the 80th percentile of this distribution.

Answer 1

The 80th percentile of the distribution is 1,490.01 grams

Explanation:

Here, we want to find the 80% of the distribution

80% means 80/100 = 0.8

We need to get the z-score equivalent to 80th percentile;

This is equal to 0.842

Mathematically;

z-score = (x - mean)/SD

we want to calculate x here;

0.842 = (x - 1400.48)/(106.33)

106.33(0.842) + 1400.48 = x

x = 1,490.00986 which is 1,490.01 grams to 2 decimal places