NCERT Solutions
Class 11 - Mathematics - Chapter 6: PERMUTATIONS AND COMBINATIONS
EXERCISE 6.4

Question. 1

If \( ^nC_8 = ^nC_2 \), find \( ^nC_2 \).

Answer:

\( ^nC_2 = 45 \)

Question. 2

Determine \( n \) if

(i) \( ^{2n}C_3 : ^nC_3 = 12 : 1 \)

(ii) \( ^{2n}C_3 : ^nC_3 = 11 : 1 \)

Answer:

(i) \( n = 5 \)

(ii) \( n = 6 \)

Question. 3

How many chords can be drawn through 21 points on a circle?

Answer:

\( 210 \)

Question. 4

In how many ways can a team of 3 boys and 3 girls be selected from 5 boys and 4 girls?

Answer:

\( 40 \)

Question. 5

Find the number of ways of selecting 9 balls from 6 red balls, 5 white balls and 5 blue balls if each selection consists of 3 balls of each colour.

Answer:

\( 2000 \)

Question. 6

Determine the number of 5-card combinations out of a deck of 52 cards if there is exactly one ace in each combination.

Answer:

\( 778320 \)

Question. 7

In how many ways can one select a cricket team of eleven from 17 players in which only 5 players can bowl if each cricket team of 11 must include exactly 4 bowlers?

Answer:

\( 3960 \)

Question. 8

A bag contains 5 black and 6 red balls. Determine the number of ways in which 2 black and 3 red balls can be selected.

Answer:

\( 200 \)

Question. 9

In how many ways can a student choose a programme of 5 courses if 9 courses are available and 2 specific courses are compulsory for every student?

Answer:

\( 35 \)

NCERT Solutions Class 11 – Mathematics – Chapter 6: PERMUTATIONS AND COMBINATIONS – EXERCISE 6.4 | Detailed Answers