Practice – Permutations & Combinations
2915
April 20, 2020
1.
2.
3.
4.
5. Total-(no. beginning with1)-(beginning with21)
6. form numbers greater than 1000
(3! , no. beginnig with 0)=18.
7. (no. beginning with 0)=100
8. 4 odd places and 4 odd nos. 3 even places (2nd, 4th, 6th)
=
9. there is only 1 way in which all lamps will be switched off
10. Two husbands can be selected out of 6 in ways
excluding the wives of above 2 husbands, 2 ladies can be selected in = ways
so, number of ways =
The above males and female can change/choose their partner in 2 ways, so total no. of ways