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NCERT Class XI Mathematics - Permutations and Combinations - Solutions

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Question : 28 of 41
Marks: +1, -0
In how many ways can one select a cricket team of eleven from 17 players in which only 5 players can bowl if each cricket team of 11 must include exactly 4 bowlers?
Solution:  
Total players = 17, No. of bowlers = 5, No. of non-bowlers = 12
No. of ways of selecting 4 bowlers =  5C4\,{}^{5}C_{4}
No. of ways of selecting 7 non-bowlers =  12C7\,{}^{12}C_{7}
∴ Required no. of ways of selecting a cricket team =  5C4\,{}^{5}C_{4} × 12C7{}^{12}C_{7}
= 5!4!×1!×12!7!×5!\frac{5!}{4! \times 1!} \times \frac{12!}{7! \times 5!} = 5 × 12×11×10×9×85×4×3×2\frac{12 \times 11 \times 10 \times 9 \times 8}{5 \times 4 \times 3 \times 2} = 3960
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