Question

in a exam 80% students are passed in English,85% are passed in math ,while 75% are passed in both .if 45 students are failed find the total no of students

Answer 1

Hy there,
Here's your answer,
let total no. of student be x.

then,student passed in english=80% of x=80/100*x=4x/5.

student passed in mathematics=85%0f x=17x/20

student passed in both subjeect=75%ofx=3x/4

total no.of student passed in either subject =4x/5+17x/20–3x/4=9x/10

total no of student failed in both subject=total no. of student-total no.of student passed in either subject.

this implies, x-9x/10 =45 (since it is given total no. of student failed=45)

solving this we get x=450.

so the total no. Of students should be 450.

Hope it helps.
Thanks.
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Answer 2

80% pass Eng
85%pass mat
75% failed both
now, failed percentage
100%-80%=20% in Eng
100%-85%=15% in Mat
100%-75%=25% in both
n(eUm)=n(e)+n(m)-n(enm)
=20+15-25
=10%
total no. of failed students= 45
10% of x=45
10/100*x=45
1/10*x=45
x=450