Permutations and Combinations:
- David has 3 shirts and 2 sweaters. In how many ways he can wear either a shirt or a sweater?
Sol: Shirts (or )Sweaters
3 ways + 2 ways = 5ways.
- David has 3 shirts and 2 sweaters. In how many ways he can wear a shirt and a sweater?
Sol: shirts (and) sweaters
3ways * 2 ways = 6ways.
- In how many ways 5 different chocolates can be distributed to 4 children such that any child can get any no. of chocolates?
Sol: children C1 C2 C3 C4
Chocolates x1 x2 x3 x4 x5
4ways *4 * 4 * 4 * 4 => 45 = 1024.
- A new flag with six vertical stripes is to be designed using some or all of the colors yellow, green, blue, and red. The no. of ways this can be done such that no two adjacent stripes have the same colour.
4 3 3 3 3 3 =>4* 35 =>4 *243
- In how many ways 5 boys can sit in 5 chairs which are in a row.
Sol: B1 B2 B3 B4 B5
CHAIRS : 5ways * 4ways * 3ways * 2ways * 1 way = 5!
N objects can be arranged in n places in n! ways.
- In how many ways 5 prizes (1st, 2nd,3rd, 4th, 5th) can be given to 5 girls ( A, B, C, D, E). Such that, each girl gets one prize.If 1st prize cannot be given to girl A or B.