Question

900 students appeared in exam to two papers of mathematics ,760 passed in paper 1 , 660 passed in paper 2, 640 students passed in both find how many students failed in both

Answer 1

hey mate ...here is ur ans.......
universal set=900 stu.
set A=760
set B=660
A intersection B=640
A union B=120+640+20
= 780
(A union B)'=900-780
=120
120 students are failed in both subjects.

Answer 2

Answer:

Answer is 140

Step-by-step explanation:

Given that n(A)=760

n(B)=660

n(A∩B)=640

therefore n(A∪B)=740+660-640=760

no.of students who failed in both the papers=n(A'∩B' )

we know that by De Morgan's law:A'∩B' =(A∪B)'

-->n(A'∩B') =n(A∪B)'

n(A∪B)'=n(U)-n(A∪B)

            =900-760(it is given that total no.of students who appeared to exam is 900 ---->n(U)=900)

            =140