Refer to the confidence interval obtained in (g). Can we conclude with 98% confi
ID: 3230025 • Letter: R
Question
Refer to the confidence interval obtained in (g). Can we conclude with 98% confidence that the population defective rate to above 0.8%? Briefly explain your answer. A courier service advertises that its average delivery time is less than 6.5 hours for local deliveries. A random sample of 14 deliveries to an address across town was recorded. These data are shown below (in hours). 8.21 3.98 4.25 5.48 4.78 6.68 7.11 7.35 6.45 2.95 7.23 4.92 3.95 5.35 Is there sufficient evidence to support the courier's advertisement, the 5% level of significance? Apply the critical value approach.Explanation / Answer
average delivery time is less than 6.5 hours
Calculating the means and standard deviation of the above data :
total numbers = 14
Mean = 5.62071
SD = 1.57133
a)
for 5% level of significance
t-value (right-tail): 1.77093340
t-value (two-tailed): +/- 2.16036866
1.77 = x - 5.62071 / 1.57133 * root(14)
x = 7.364
Hence as at 5% level of significance the mean time is less than 6.5 hours