In a group of students, 100 students know Hindi, 50 know English and 25 know both.

Let us assume that,

U = the set of all students in the group

E = the set of students who know English

H = the set of the students who know Hindi

H ∪ E = U

Given that,

Number of students who know Hindi n (H) = 100

Number of students who knew English, n (E) = 50

Number of students who know both, n (H ∩ E) = 25

We have to find the total number of students in the group i.e. n (U)

According to the question,

n (U) = n(H) + n(E) – n(H ∩ E)

= 100 + 50 – 25

= 125

Total number of students in the group = 125 students