Question

Heights for college women are normally distributed with a mean of 65 inches and standard deviation of 2.7 inches. Find the 25^th percentile.

Suppose that the time students wait on a bus can be described by a uniform random variable X, were X is between 0 and 60 minutes. What is the probability they will have to wait between 25 and 35 minutes for the next bus?

Answer 1

SOLUTION:

Given that,

mean = = 65

standard deviation = = 2.7

Using standard normal table,

P(Z < z) = 25%

= P(Z < z) = 0.25

= P(Z < -0.67) = 0.25

z =-0.67 Using standard normal z table,

Using z-score formula  

x= z * +

x= -0.67*2.7+65

x= 63.191

SOLUTION

Given that,

a = 0

b = 60

P(c < x < d) = (d - c) / (b - a)

P(25 < x < 30) = (30 - 25) / (60 - 0)=0.0833

PROBABILITY =0.0833