Question

Nationwide, the amount charged by doctors for performing a particular minor surgical procedure averages $1525 and varies with a standard deviation of $375. We randomly select 50 bills from the population of all bills charged for this surgery. Let x represent the average amount charged for these 50 surgical procedures. Calculate the probability that the average amount charged for this procedure is more than $1200

Answer 1

Solution :

Given that,

mean = = $ 1525

standard deviation = = $ 375

n = 50

=   = $ 1525

= / n = $ 375 / 50 = 53.03

P( > 1200) = 1 - P( < 1200)

= 1 - P[( - ) / < (1200 - 1525) / 53.03]

= 1 - P(z <-6.13)

Using z table,    

= 1 - 0

= 1