Question
7 children are to be selected from a group of 8 boys and
6 girls. In how many ways will the children with at most 3 girls and at least 4 boys be selected?Solution
Case I:  4 boys and 3 girls can be selected, Number of ways of selection = 8C4 × 6C3 = 70 × 20 = 1400 Case II: 5 boys and 2 girls can be selected, Number of ways of selection = 8C5 × 6C2 = 56 × 15 = 840 Case III: 6 boys and 1 girl can be selected, Number of ways of selection = 8C6 × 6C1 = 28 × 6 = 168 Case IV: 7 boys can be selected, Number of ways of selection = 8C7 = 8 So, total number of ways of selecting the children = 1400 + 840 + 168 + 8 = 2416 ways
Find the wrong number in the given number series.
11, 30, 67, 133, 219, 346
- Find the wrong number in the given number series.
12, 16, 25, 50, 99, 200 970, 934, 920, 893, 884, 880
- 80, - 44, - 4, 88, 216, 380
126, 295, 520, 807, 1170, 1611
32, 41, 66, 115, 236, 415
Find the wrong number in the given number series.
30, 26, 24, 18, 14, 10
8, 17, 35, 71, 143, 287
224, 183, 144,115, 86, 63, 44.
Find the wrong no in the given number series.
175, 319, 488, 694, 909, 1165