problem-5.16

problem-5.16  We assume that the scores are normally distributed. A student picked at random has a score that is assumed to be normally distributed with mean 20.6 and 5.5. We compute \PROB(X > 22) with
> 1 - pnorm(22,20.6,5.5)
[1] 0.3995
    
Thus, about 40% of the students passed the exam.
How many more would be expected to fail if the mark were moved? We multiply the probability times the sample size to get
> 1000000 * diff(pnorm(c(22,23), mean=20.6, sd=5.5))
[1] 68251