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Quiz 2
Chapters 4 & 5__TEAM A week 5________________________

1) Use the standard normal distribution to find P(-2.25 < z < 1.25). A) .0122B) .8821C) .8944D) .4878
P(-2.25 < z < 1.25) = F(1.25) - (1 - F(2.25)) = 0.89435 - (1 - 0.987776) = 0.882126

2) Before a new phone system was installed, the amount a company spent on personal calls followed a normal distribution with an average of $ 900 per month and a standard deviation of $50 per month. Refer to such expenses as PCE's (personal call expenses). Using the distribution above, a. what is the probability that during a randomly selected month PCE's were between $775.00 and $990.00? A) .0421B) .0001C) .9999D) .9579

b. what is the probability that during a randomly selected month PCE's were between $375.00 and $590.00? A) .9579B) .9999C) 2.82316E-10D) .0421

c Find the point in the distribution below which 2.5% of the PCE's fell. A) $ 682.50B) $ 602.00C) $ 802.00D) $ 17.50

3) The diameters of ball bearings produced in a manufacturing process can be described using a uniform distribution over the interval 2.5 to 4.5 millimeters. What is the probability that a randomly selected ball bearing has a diameter greater than 3.2 millimeters? A) 1.5B) 0.4571C) 0.7111D) 0.65

4) A machine is set to pump cleanser into a process at the rate of 9 gallons per minute. Upon inspection, it is learned that the machine actually pumps cleanser at a rate described by the uniform distribution over the interval 8.5 to 12.5 gallons per minute.

a. What is the probability that at the time the machine is checked it is pumping more than 10.5 gallons per minute?

A) .50B) .25C) .7692D) .667

b. What is the probability that at the time the machine is checked it is pumping more than 9.0 gallons per minute? A) .7692B) .25C) .50D) .875

c. What is the probability that at the time the machine is checked it is pumping between 9.5and 10.5 gallons per minute?

A) .50B) 667C) .7692 D) .25...
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