Question

In a city of 1000 population, all people read newspaper. 600 people read Hindustan Times and 700 people read Times of India. How many people read only Hindustan Times?

(a) 100

(b) 200

(c) 300

(d) 600

I have been asked this question in an international level competition.

This intriguing question originated from Practical Problems on Union and Intersection of Two Sets in division Sets of Mathematics – Class 11

Answer 1

Right answer is (c) 300

To explain: Since all people read newspaper so, n (T ∪ H) = 1000.

n(H) = 600 and n(T) = 700.

n (T ∪ H) = n (T) + n (H) – n (T ∩ H)

1000 = 700 + 600 – n (T ∩ H)

n (T ∩ H) = 1300-1000 = 300.

n (T’ ∩ H) = n(H)- n (T ∩ H) = 600-300 = 300.

300 persons read only Hindustan Times.