Question 1189638: Answer ALL Questions
1. The time it takes a student to finish a chemistry test is uniformly distributed between 50 and 70 minutes.
a. What is the probability density function for this uniform distribution?
b. Find the probability that a student will take between 40 and 60 minutes to finish the test.
c. Find the probability that a student will take no less than 55 minutes to finish the test.
d. What is the expected amount of time it takes a student to finish the test?
e. What is the standard deviation for the amount of time it takes a student to finish the test?
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! It is a rectangular density function with probability 0.05 for the width, and length 20 minutes.
probability is 1/(b-a) in the range of the distribution, 0 otherwise.
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b. This is essentially between 50 and 60 minutes, and the probability is 1/2.
c. No fewer than 55 minutes is 15/20 or 0.75 probability.
d. Expected value is the mean, or the middle, and that is (1/2)(a+b)=60 minutes
e. sd is (b-a)/sqrt(12)=20/sqrt(12)=5.77 minutes
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