2. A certain brand of flood lamps has a lifetime that is normally distributed with a mean of

3,750 hours and a standard deviation of 300 hours.

a. What proportion of these lamps will last for more than 4,000 hours?

b. What proportion of these Lams will last less than 3,600 hours?

c. What proportion of these lamps will last between 3,800 and 4,100 hours?

(6 marks)

d. What lifetime should the manufacturer advertise for these lamps in order that only

2% of the lamps will burn out before the advertised lifetime?

(6 marks)

Effective date 06/09/2019

(5 marks)

(5 marks)

Page 1 of 4