Advertisements
Advertisements
प्रश्न
If nPr = 720(nCr), then r is equal to:
विकल्प
4
5
6
7
Advertisements
उत्तर
6
Explanation:
Given nPr = 720(nCr)
`(n!)/((n-r)!) = 720 (n!)/(r!(n-r)!)`
1 = `720/(r!)`
r! = 720
r! = 6 × 5 × 4 × 3 × 2 × 1
r! = 6!
r = 6
APPEARS IN
संबंधित प्रश्न
Verify that 8C4 + 8C3 = 9C4.
How many chords can be drawn through 21 points on a circle?
If four dice are rolled, find the number of possible outcomes in which atleast one die shows 2.
If a polygon has 44 diagonals, find the number of its sides.
Prove that 15C3 + 2 × 15C4 + 15C5 = 17C5
Prove that if 1 ≤ r ≤ n then `"n" xx ""^(("n" - 1))"C"_("r" - 1) = ""^(("n" - "r" + 1))"C"_("r" - 1)`
7 relatives of a man comprises 4 ladies and 3 gentlemen, his wife also has 7 relatives; 3 of them are ladies and 4 gentlemen. In how many ways can they invite a dinner party of 3 ladies and 3 gentlemen so that there are 3 of man’s relative and 3 of the wife’ s relatives?
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 in which a host lady invite 8 people for a party of 8 out of 12 people of whom two do not want to attend the party together is
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
