In: Statistics and Probability
The mean price for regular gasoline at the pump was $2.877 per gallon and the standard deviation was $0.009 per gallon. A random sample of size 55 is drawn from this population. What is the probability that the mean price per gallon is less than $2.876?
Solution :
Given that ,
mean = = 2.877
standard deviation = = 0.009
n = 55
= 2.877
= / n = 0.009/ 55 =0.0012
P( < 2.876) = P[( - ) / < (2.876-2.877) /0.0012]
= P(z <-0.83 )
Using z table
=0.2033
probability= 0.2033