Question

The length of a social media video is normally distributed with a mean of 3.91 seconds and a standard deviation of 0.06 seconds. What percent of videos are between 3.73 and 4.09 seconds? a2% b5% c95% d98%

Answer 1

Remember that

z =(x - μ)/σ

where

μ=3.91 sec

σ=0.06 sec

Find out the value of Z for x=3.73 sec

z1=(3.73-3.91)/0.06

z1=-3

Find out the value of Z for x=4.09 sec

z2=(4.09-3.91)/0.06

z2=3

using a z score table value

P(3.73 < X < 4.09)=0.9973

therefore

the answer is

d 98%