Question

In an examination 80% passed in English, 85% passed in
Mathematics but 75% passed in both the subjects. If only 45 examinees failed
in both the subjects then find the number of examinees.​

Answer 1

Answer:

400

Step-by-step explanation:

Let the total number of student is x

Number of student passed in both subject is

n(A∪B)=n(A)+n(B)−(A∩B)

Here, n(A)=80% of x

n(B)=85% of x

n(c)=75% of x

∴n(A∪B)=

100

80

x+

100

85

x−

100

75

x

⇒

100

90x

⇒

10

9x

Failed in both subjects

⇒x−

10

9x

⇒

10

x

∴

10

x

=40

⇒x=400