Advertisements
Advertisements
प्रश्न
If nC12 = nC9 find 21Cn
Advertisements
उत्तर
Given nC12 = nC9
We have nCx = nCy
⇒ x = y or x + y = n
nC12 = nC9
⇒ 12 + 9 = n
⇒ n = 21
⇒ 21Cn = 21C21 = 1
APPEARS IN
संबंधित प्रश्न
If nPr = 1680 and nCr = 70, find n and r.
Verify that 8C4 + 8C3 = 9C4.
Out of 7 consonants and 4 vowels, how many words of 3 consonants and 2 vowels can be formed?
A committee of 5 is to be formed out of 6 gents and 4 ladies. In how many ways this can be done when
- atleast two ladies are included.
- atmost two ladies are included.
Let there be 3 red, 2 yellow and 2 green signal flags. How many different signals are possible if we wish to make signals by arranging all of them vertically on a staff?
If nPr = 720(nCr), then r is equal to:
The number of diagonals in a polygon of n sides is equal to
There are 10 true or false questions in an examination. Then these questions can be answered in
The value of (5C0 + 5C1) + (5C1 + 5C2) + (5C2 + 5C3) + (5C3 + 5C4) + (5C4 + 5C5) is:
Thirteen guests have participated in a dinner. The number of handshakes that happened in the dinner is:
A trust has 25 members. How many ways 3 officers can be selected?
How many ways a committee of six persons from 10 persons can be chosen along with a chair person and a secretary?
There are 5 teachers and 20 students. Out of them a committee of 2 teachers and 3 students is to be formed. Find the number of ways in which this can be done. Further find in how many of these committees a particular student is excluded?
In an examination a student has to answer 5 questions, out of 9 questions in which 2 are compulsory. In how many ways a student can answer the questions?
Determine the number of 5 card combinations out of a deck of 52 cards if there is exactly three aces in each combination
A committee of 7 peoples has to be formed from 8 men and 4 women. In how many ways can this be done when the committee consists of at most 3 women?
How many triangles can be formed by 15 points, in which 7 of them lie on one line and the remaining 8 on another parallel line?
There are 11 points in a plane. No three of these lies in the same straight line except 4 points, which are collinear. Find, the number of straight lines that can be obtained from the pairs of these points?
Choose the correct alternative:
The number of ways of choosing 5 cards out of a deck of 52 cards which include at least one king is
Choose the correct alternative:
The product of first n odd natural numbers equals
