Question

A racing car consumes a mean of 106 gallons of gas per race with a standard deviation of 6 gallons.

If 45 racing cars are randomly selected, what is the probability that the sample mean would be less than 104.7 gallons? Round your answer to four decimal places.

Answer 1

Solution :

Given that ,

mean =   = 106

standard deviation = σ   =6

n =45

= 106

=  / n = 6 / 45=0.8944

P( <104.7 ) = P[( - ) / < (104.7 -106) / 0.8944]

= P(z <-1.45 )

Using z table  

= 0.0735   

probability= 0.0735