1.The Rockwell hardness X of certain metal pins is known to have a mean of M = 50 and a standard deviation 0 = 4 Assume that the distribution of all such pin hardness measurements is known to be normal. Suppose a pin is randomly selected from the population. What is the probability that the hardness of this pin is less than 46? That is, what is the probability P(X < 46)? Choices: 0.3085 0.0228 0.0 0.01587 0.8413 0.0668
1.The Rockwell hardness X of certain metal pins is known to have a mean of M = 50 and a standard deviation 0 = 4
Assume that the distribution of all such pin hardness measurements is known to be normal.
Suppose a pin is randomly selected from the population. What is the probability that the hardness of this pin is less than 46? That is, what is the probability P(X < 46)?
Choices:
0.3085
0.0228
0.0
0.01587
0.8413
0.0668
2.Assume T is a random variable representing time, with an exponential
distribution and a mean of 21.
Find the probability P(T <= 21).
3.The wait times at a clinic are exponentially distributed with a mean wait time
of 40 minutes.
What is the median wait time at the ER?
Choices:
19.45 minutes
40 minutes
44 minutes
27.73 minutes
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