In a group of 1000 people, there are 750 people who can speak Hindi and 400 who can speak English. How many can speak Hindi only?

Given in the question,
n(H ∪ E) = 1000, n(H) = 750, n(E) = 400
Use the below formula,
n(H ∪ E) = n(H) + n(E) – n(H ∩ E)
We get 1000 = 750 + 400 – n(H ∩ E)
⇒ n(H ∩ E) = 1150 – 1000 = 150.
Number of People who can speak Hindi only
= n(H ∩ E′) = n(H) – n(H ∩ E)
= 750 – 150 = 600.