A study by Bechtel et al., 2009, described in the Archives o…

A study by Bechtel et al., 2009, described in the Archives of Environmental & Occupational Health considered polycyclic aromatic hydrocarbons and immune system function in beef cattle. Some cattle were near major oil- and gas-producing areas of western Canada. The mean monthly exposure to PM1.0 (particulate matter that is in diameter) was approximately 7.2 with standard deviation 1.5. Assume that the monthly exposure is normally distributed. What is the probability of a monthly exposure between 3 and 5 ?

Computer keyboard failures are due to faulty electrical conn…

Computer keyboard failures are due to faulty electrical connects (12%) or mechanical defects (88%). Mechanical defects are related to loose keys (27%) or improper assembly (73%). Electrical connect defects are caused by defective wires (35%), improper connections (13%), or poorly welded wires (52%). Find the probability that a failure is due to improperly connected or poorly welded wires.

The speed of a file transfer from a server on campus to a pe…

The speed of a file transfer from a server on campus to a personal computer at a student’s home on a weekday evening is normally distributed with a mean of 63 kilobits per second and a standard deviation of four kilobits per second. What is the probability that the file will transfer at a speed of 70 kilobits per second or more?