Question

X has a normal distribution with the given mean and standard deviation. Find the indicated probability. (Round your answer to four decimal places.)

μ = 39, σ = 20, find

P(34 ≤ X ≤ 46)

Answer 1

Solution :

Given that ,

mean = = 39

standard deviation = =20   

P(34 ≤ X ≤ 46) = P[(34-39) / 20< (x - ) / < (46-39) /20 )]

= P( -0.5< Z <0.35 )

= P(Z <0.35 ) - P(Z <-0.5 )

Using z table   

=  0.6368 - 0.3085

probability= 0.3283