Question

The patient recovery time from a particular surgical procedure is normally distributed with a mean of 4.1 days and a standard deviation of 2.3 days.

What is the probability of spending between 2 and 7 days in recovery?

Answer 1

Solution :

Given that ,

mean = = 4.1

standard deviation = = 2.3

P(2< x <7 ) = P[(2-4.1) /2.3 < (x - ) / < (7-4.1) /2.3 )]

= P(-0.91 < Z <1.26 )

= P(Z < 1.26) - P(Z < -0.91)

Using z table   

= 0.8962 - 0.1814

probability= 0.7148