Question

Amount of time students study for a midterm test is normally distributed with a mean of 25 hours and a standard deviation of 4.0 hours. What's the probability that one will study for between 24 & 26 hours?

Answer 1

Solution :

Given that ,

mean = = 25

standard deviation = = 4

P(24< x < 26) = P[(24-25) /4 < (x - ) / < (26-25) /4 )]

= P(-0.25 < Z < 0.25)

= P(Z <0.25 ) - P(Z <-0.25 )

Using z table   

=  0.5987-0.4013

probability= 0.1974