In a class test, out of N students, if only 1/3 of passed in science and, of those who passed in science subject, 1/5 also passed in maths subject, how many students did not pass in both subjects ?  Choose the most appropriate option: A) N/15 B) 4N/15 C) 14N/15 D) N/5 E) 4N/5
1/3 of tested passed in Science, thus N/3 had passed in science.   Of those who passed in science, 1/5 also had passed in maths, thus 1/5*N/3 = N/15 had passed in both subjects.   Therefore, N - N/15 = 14N/15 did not pass in both subjects.   Answer: 14N/15.
<result>C</result>
In a class test, out of N students, if only 1/3 of passed in science and, of those who passed in science subject, 1/5 also passed in maths subject, how many students did not pass in both subjects ?