n a written test given to a large class comprising 42 students, the test scores were found to be normally distributed with a mean of 78 and a standard deviation of 7. A minimum score of 60 was needed to pass the test. A score of 90 or greater was needed to earn an A in the test. Answer the following questions;
a) What is the probability that a randomly selected student would pass the test?
b) What percentage of students earned an A?
==here is what i have
== a)for stduent to pass then test P(X>60)=1-P(X<60)=1-P(Z<(60-78)/7)=1-P(Z<-2.5714)=1-0.0051=0.9949
b) for student to get A grade P(X>90)=1-P(X<90)=1-P(Z<(90-78)/7)=1-P(Z<1.7143)=1-0.9568=0.0432
total number of student who got A grade =0.0432*42=1.8144
is this correct.
3 answers
I agree with it, but I find I would like to meet that .8144 of a person.
Should I round up or round down?
To round to whole people, you would round up if it was .5 of a person or greater.
2 answers