Robertson Employment Service customarily gives standard intelligence and aptitude tests to all people who seek employment through the firm. The firm has collected data for several years and has found that the distribution of scores is not normal, but is skewed to the left with a mean of 86 and a standard devistion of 16. What i sthe probability that in a sample of 75 applicants who take the test, the mean score will be less than 84 or greater than 90?
An oil refinery has backup monitors to keep track of the refinery flows continuously and to prevent machine malfunctions from disrupting the standard deviation of 730 hours. In addition to the primary monitor the refinery has set up two standby units, which are duplicates of the primary one. In the case of malfunction of tone of the monitors, another will automatically take over in its place. The operating life of each monitor is independent of the others.