# Statistics Questions: Probabilities based on Poisson distributions

1. The mean life of a computer disk drive is 2,000 hours. The standard deviation is 140 hours. Assuming the life-time of the drives to be normally distributed, find the probability of a disk drive lasting more than 1,800 hours.

a. .4236

b. .9236

c. .8472

d. .5764

e. .2118

f. None of the above.

2. The yearly commissions per salesperson employed by a manufacturer of light machinery average $40,000 with a standard deviation of $5,000. What percent of the salespersons earn between $32,000 and $42,000?

a. 60.06%

b. 39.94%

c. 34.13%

d. 65.87%

e. 81.66%

f. None of the above.

3. A study of 200 stamping firms revealed these incomes after taxes:

Income After Taxes Number of Firms

Under $1 million 102

$1 million up to $20 million 61

$20 million and more 37

What is the probability that a particular firm selected has under $1 million in income after taxes?

a. 0.000

b. 0.250

c. 0.333

d. 0.510

e. None of the above.

4. A study of the opinion of designers with respect to the primary color most desirable for use in executive offices showed that:

Primary Color Number of Opinions

Red 92

Orange 86

Yellow 46

Green 91

Blue 37

Indigo 46

Violet 2

What is probability that a designer does not prefer red?

a. 1.000

b. 0.770

c. 0.000

d. 0.230

e. None of the above.