Problem 6 and 7 6,(5pts) Let x denote the time in hours needed to locate and cor
ID: 3351841 • Letter: P
Question
Problem 6 and 7
6,(5pts) Let x denote the time in hours needed to locate and correct a problem in the software that governs the timing of the traffic lights in Downtown Area of Beirut. Assume that x is normally distributed with a mean of 10 hours and a variance of 9. Find the number of hours required to complete the fastest 5% of the repairs? pret)20.os 7. (10pts) A firm has two possible sources for selecting a maintenance company for its mainframe computers. Company X charges an average repair and maintenance cost of $526 per month with a standard deviation of S115, while company Y charges an average repair and maintenance cost of $620 per month with a standard deviation of $182. What is the probability that a random sample of 32 months of repair and maintenance costs of company X will ayke a mean cod mainienane costs of a sample of 45 months from company Y?Explanation / Answer
6)for fastest 5% at 5 percentile ; z score =-1.64
therefore required number of hours =mean+z*std deviation=10-1.64*3=5.08 Hours
7)
here let differnce is A=Xavg-Yavg
mean of A =526-620=-94
and std deviation of A =(1152/32+1822/45)1/2 =33.9024
hence probability =P(A<-80)=P(Z<(-80-(-94))/33.9024)=P(Z<0.4130)=0.6602