Question

A professor at a local university noted that the grades of her students were normally distributed with a mean of 78 and a standard deviation of 10. if 12.1 percent of her students failed the course and received f's, what was the maximum score among those who received an f?

Answer 1

x=mean+Z*SD
Where, x=maximum score for those who received "f", mean = 78, Z value from Z tables at 12.1% (0.121) score and SD = standard deviation.

At 0.121, Z ≈ -1.17

Therefore,
x=78-1.17*10 = 66.3%