Question

The lengths of adult males' hands are normally distributed with mean 190mm and the standard deviation is 7.7mm. Suppose that 49 individuals are randomly chosen.

What is the probability that the average length of the 49 randomly selected male hands is less than 188.9 mm

Answer 1

Solution :

Given that ,

mean = = 190

standard deviation = = 7.7

n = 49

= 190

=  / n = 7.7/ 49=1.1

P( <188.9 ) = P[( - ) / < (188.9-190) /1.1 ]

= P(z < -1)

Using z table  

= 0.1587