CIVL 3103 Exam 1 Review

1. If P(A) = 0.80, P(C) = 0.35, and P(A∩C) = 0.28, are events A and C independent?

2. Use Venn diagrams to verify that:

a. ( ) 'A B A B=U I

b. ( ) 'A B A B=I U 3. A large chain retailer purchases a certain kind of electronic device from a

manufacturer. The manufacturer indicates that the defective rate of the device is 3%. The inspector of the retailer randomly picks 20 items from a shipment. What is the probability that there will be at least one defective item among these 20?

4. Cotton linters used in the production of rocket propellant are subjected to a

nitration process that enables the cotton fibers to go into solution. The process is 90% effective in that the material produced can be shaped as desired in a later processing stage with probability 0.9. What is the probability that exactly 20 lots will be produced in order to obtain the third defective lot?

5. 3.30

6. Measurements of compressive strength, in psi, were made on 90 concrete blocks.

The measurements were taken to investigate the variability among blocks purchased from a particular supplier. The resulting compressive strength measurements are described by the histogram below.

a. Approximately how many blocks had a compressive strength between 40 and 52 psi?

b. Convert the frequency histogram to a relative frequency histogram.

c. Approximately what proportion of the blocks had compressive strengths exceeding 56 psi?