WeeG

08-02-2010, 02:44 AM

Hello,

I need a wee help with this question...

"A company that repair computers go with the next sale:

If the waiting time of a customer for a technician is at least as long as the time

of the repair itself, the customer will pay 55$. On the other hand, if the waiting

time for a technician is less that the time of the repair, the customer will pay

95$.

The waiting time for a technician is a normal random variable with mean of 8

hours and standard deviation of 75 minutes.

The time of repair is also a normal random variable with mean of 6 hours and

a standard deviation of 150 minutes.

Assume that the times are independent."

1. Calculate the probability that a customer will pay 55$.

2. Calculate the variance of payment of a customer to the company.

3. The company has decided to give bonus to it's workers if the profit from

repairing computers will be more than 7500$. How many customers do they

need to serve so the probability of getting the bonus will be more than

0.67 ?

I wouldn't know where to start, I mean, I think I have some clue on "1", but not on "2" and "3" ... help !! :o

I need a wee help with this question...

"A company that repair computers go with the next sale:

If the waiting time of a customer for a technician is at least as long as the time

of the repair itself, the customer will pay 55$. On the other hand, if the waiting

time for a technician is less that the time of the repair, the customer will pay

95$.

The waiting time for a technician is a normal random variable with mean of 8

hours and standard deviation of 75 minutes.

The time of repair is also a normal random variable with mean of 6 hours and

a standard deviation of 150 minutes.

Assume that the times are independent."

1. Calculate the probability that a customer will pay 55$.

2. Calculate the variance of payment of a customer to the company.

3. The company has decided to give bonus to it's workers if the profit from

repairing computers will be more than 7500$. How many customers do they

need to serve so the probability of getting the bonus will be more than

0.67 ?

I wouldn't know where to start, I mean, I think I have some clue on "1", but not on "2" and "3" ... help !! :o