InterviewSolution
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InterviewSolution
| 1. |
In a class there are 20 boys and 15 girls. In how many ways can 2 boys and 2 girls be selected?A. `.^(35)C_(4)`B. `.^(35)C_(2)`C. `.^(20)C_(2)xx.^(15)C_(2)`D. `20xx15` |
| Answer» r objects can be selected from b objects in `.^(n)C_(r)` ways. Now use the fundamental principle. i.e., task `T_(1)` can be done in m ways and task `T_(2)` can be done in n ways, then the two tasks can be done simultaneously in mn ways. | |