Many companies "grade on a bell curve" to compare the performance of their managers and professional workers. this forces the use of some low performance ratings so that not all workers are listed as "above average." ford motor company’s "performance management process" for a time assigned 10% a grades, 80% b grades, and 10% c grades to the company's 18,000 managers.
suppose that ford's performance scores really are normally distributed. this year, managers with scores less than 35 received c's and those with scores above 425 received a's. what are the mean and standard deviation of the scores?
a. μ = 230.0 and σ = 152.3
b. μ = 230.0 and σ = 167.5
c. μ = 230.0 and σ = 140.3
d. μ = 225.0 and σ = 152.3
e. μ = 250.0 and σ = 175.8
f. μ = 250.0 and σ = 168.6