In: Statistics and Probability
A recent study by the Greater Los Angeles Taxi Drivers Association showed that the mean fare charged for service from Hermosa Beach to Los Angeles International Airport is $18 and the standard deviation is $3.00. We select a sample of 15 fares. What is the likelihood that the sample mean is between $17 and $19? Assume the population of fares is normally distributed. (Round z value to 2 decimal places and final answer to 4 decimal places.)
Solution :
Given that,
mean = 
 = 18
standard deviation = 
 = 3
n = 15

= 
 = 18

= 
 / 
n = 3 / 
15 = 0.7746
P(17 < 
 < 19) = P((17 - 18) / 0.7746 <(
- 
)
/ 
< (19 - 18) / 0.7746))
= P(-1.29 < Z < 1.29)
= P(Z < 1.29) - P(Z < -1.29) Using z table,
= 0.9015 - 0.0985
= 0.8030