The amount of time that the customer spends waiting at airport check-in counter is random variable with mean 8.4 minutes and standard deviation 1.7 minutes. Assume that the random sample of n=46 customers is observed. Determine the probability that average time waiting in line for these customers is
(a) Less than 10 minutes
(b) Between 5 and 10 minutes
(c) Less than 6 minutes
Round your answers to one decimal place (e.g. 98.7).