The lifetime of ‘Bestvision’ TV picture tubes is normally distributed, with a mean of 8 years and standard deviation of 2 years.A. What is the probability that a picture tube will

last more than 10 years?B. If the firm guarantee the picture tube for 2 yrs,

what percentage of the tubes will have to be replaced?

C. If the firm is willing to replace the picture tubes in a maximum of 1 percent of the television set sold, what guarantee period can be offered for the TV’s picture tube?

The average monthly sales of ‘Reliable’ computers are 2500 units with a standard deviation of 100 units. The sales are found to be normally distributed over months.1. Determine the probability that the sales during a

particular month will be at least 2400.2. A new monthly sales target is to be set, which, at

present corresponds to 5% of sales. What should the new sales target be?

Jarrid Medical, Inc., is developing a compact kidney dialysis machine, but its chief engineer, Mike Crowe, is having trouble controlling the variability of the rate at which fluid moves through the device. Medical standards require the hourly flow be 4 liters, plus or minus 0.1 liters, 80 percent of the time. Mr. Crowe, in testing the prototype, has found that 68 percent of the time, the hourly flow is within 0.08 liter of 4.02 liters. Does the prototype satisfy the medical standards

In a normal distribution with standard deviation of 5.0, the probability that an observation selected at random exceeds 21 is 0.14.a. Find the mean of the distribution.b. Find the value below which 4 percent of the

values in the distribution lie.

The manager of a Spiffy Lube auto lubrication shop is trying to revise his policy on ordering grease gun cartridges. Currently, he orders 110 cartridges per week, but he runs out of cartridges 1 out of every 4 weeks. He knows that, on average, the shop uses 95 cartridges per week. He is also willing to assume that demand for cartridges is normally distributed.A. What is the SD of the distribution?B. If the manager wants to order enough cartridges

so that his probability of running out during any week is no greater than 0.2, how many cartridges should he order per week?

Maurine Lewis, an editor for a large publishing company, calculates that it requires 11 months on average to complete the publication process from manuscripts to finished book, with a standard deviation of 2.4 months. She believes that the normal distribution well describes the distribution of publication times. Out of 19 books she will handle this year, approximately how many will complete the process in less than a year?