Question

If the XAT centre of 4 students can be any one of the 7 cities, then calculate the probability that all the 4 students get any one of exactly 2 centres.

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Total number of ways in which centres can be allocated = 7⁴. Two centres can be chosen in ⁷C₂ ways. The number of ways they can accommodate 4 students = 2⁴

But this includes the two cases where one centre is having all the four students. So, no. of ways = 2⁴ – 2 = 14. So, total number of favourable ways = ⁷C₂ × 14

So, probability = ⁷C₂ × =.

Hence option (b)