Question

In an examination out of 1200 candidates 80% boys and 70% girls passed. If the total percentage of passed candidates be 75, what is the number of boys who appeared in the examination?

Answer 1

●● Question ●●

In an examination out of 1200 candidates 80% boys and 70% girls passed. If the total percentage of passed candidates be 75% , what is the number of boys who appeared in the examination?

●● Solution ●●

Let,

no. of boys appeared for exam = x

and

no. of girls appeared for exam = y

then,

x + y = 1200

x = 1200 - y ..... eqn(1)

______________________________

percentage of boys passed = 80%

no. of boys passed = (80/100)*x= 8x /10

percentage of girls passed = 70%

no. of girls passed =(70/100)*y = 7y/10

................................................................

Total no.of students passed=(8x/10)+(7y/10)

given,

percentage of students passed= 75%

so,

no. of students passed = 75/100*1200

no. of students passed = 900

So,

(8x/10) + (7y/10) = 900

taking LCM

(8x + 7y )/10 = 900

cross multiplying

8 x + 7y = 9000

Using eqn(1) substituting value of x

8 (1200 - y) +7y = 9000

9600 -8y + 7y = 9000

y = 600

putting value of y in eqn(1)

x = 1200 - 600

x = 600

Therefore,

no. of boys who appeared in the

examination is 600.