Permutation & Combination

Quantitative Aptitude (CGL)

Title

45:30

8 of 24 completed

5 of 15 completed

38 of 100 completed

8 of 20 completed

Indian Economy - Understanding the basics of Indian economic system

There are 28 persons present at a press conference. After the conference they all shake hands with each other. If 7 of them

refuse to shake hands at all, then how many hands shakes will be there altogether?

This questions was previously asked in

SSC CGL 17th August 2021 Shift-3

378

231

420

210

- Total people: 28

- 7 refuse to shake hands, so 28 - 7 = 21 people shake hands.

- Each of the 21 shakes hands with the others: calculated using 21 choose 2.

- Formula for handshakes: \( \frac{21 \times 20}{2} = 210 \).

- Option:1, 378 - Incorrect; possibly 28 choose 2 without exclusions.

- Option:2, 231 - Incorrect; does not fit increment criteria.

- Option:3, 420 - Incorrect; double of correct option, likely error.

- Option:4, 210 - Correct answer for 21 people shaking hands.