Question

IN A EXAMINATION 30 % STUDENTS FAILED IN ENGLISH AND 20 % FAILED IN MATHS AND 5 % FAILED IN BOTH THE SUBJECT . IF 275 STUDENTS PASSED IN BOTH THE SUBJECT. FIND THE NUMBER OF STUDENTS FAILED ONLY IN ENGLISH

Answer 1

Answer:

5% failed in both means 95 % passed in both

95%=275 ( given)

let total number of children be x

95% of x = 275

95/100 * x = 275

x = 275*100/95

x = 290

30 % failed in English

30 % of 290

30/100 * 290

= 29*3

= 87 ( answer)

Answer 2

Step: 1

By the question ,

Let , the whole student number

= x

a.Failed student in english exam

= (x*30)/100

= 3x/10

b.Failed student in maths exam

= (x*20)/100

= x/5

c.Faied student in both exam

=( x*5)/100

= x/20

Step:2

By De morgan theorem

(AUB) = A + B - (AnB)

By this , let ,

A= 3x/10

B= x/5

( AnB)= x/20

Apply de morgan' s theorem

(AUB) = 3x/10 + x/5 - x/20

= 9x/20

(AUB), represents the number of students failed in both and any one of these exam.

Step:3 by the question we made a equation

x - 9x/20 = 275

x = 500

a. It mean the whole student appear in exam is 500.

Step :4

Student failed in english exam

=( 500*30)/100

= 150

Step:5

Answer:- the number of student failed in english exam only is 150 .