Advertisements
Advertisements
प्रश्न
Evaluate `("n"!)/("r"!("n" - "r")!)` when n = 10, r = 3
Advertisements
उत्तर
n = 10, r = 3
`("n"!)/("r"!("n" - "r")!) = (10!)/(3!(10 - 3)!)`
= `(10!)/(3!7!)`
=`(10 xx 9 xx 8 xx 7!)/(3 xx 2 xx 1 xx 7!)`
= `(10 xx 9 xx 8)/(3 xx 2 xx 1)`
= 10 × 3 × 4
= 120
APPEARS IN
संबंधित प्रश्न
How many 3-digit numbers can be formed from the digits 1, 2, 3, 4 and 5 assuming that repetition of the digits is not allowed?
How many 4-letter code can be formed using the first 10 letters of the English alphabet, if no letter can be repeated?
Given 5 flags of different colours, how many different signals can be generated if each signal requires the use of 2 flags, one below the other?
A Signal is generated from 2 flags by putting one flag above the other. If 4 flags of different colours are available, how many different signals can be generated?
How many two-letter words can be formed using letters from the word SPACE, when repetition of letters is not allowed?
How many numbers between 100 and 1000 have the digit 7 exactly once?
Select the correct answer from the given alternatives.
A college has 7 courses in the morning and 3 in the evening. The possible number of choices with the student if he wants to study one course in the morning and one in the evening is -
How many two-digit numbers can be formed using 1, 2, 3, 4, 5 without repetition of digits?
In how many ways 5 persons can be seated in a row?
How many three-digit numbers are there with 3 in the unit place?
without repetition
How many three-digit numbers, which are divisible by 5, can be formed using the digits 0, 1, 2, 3, 4, 5 if repetition of digits are not allowed?
How many three-digit numbers, which are divisible by 5, can be formed using the digits 0, 1, 2, 3, 4, 5 if repetition of digits are allowed?
Find the value of 3! – 2!
Choose the correct alternative:
There are 10 points in a plane and 4 of them are collinear. The number of straight lines joining any two points is
How many numbers are there between 99 and 1000 having atleast one of their digits 7?
If the letters of the word RACHIT are arranged in all possible ways as listed in dictionary. Then what is the rank of the word RACHIT?
There will be only 24 selections containing at least one red ball out of a bag containing 4 red and 5 black balls. It is being given that the balls of the same colour are identical.
The number of all four digit numbers which begin with 4 and end with either zero or five is ______.
