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Let  S={1,2,3.......,9} For k=1,2,...5 , Let N_k be the number of subsets of S, each containing five elements out of which exactly k are odd. Then N₁+N₂+N₃+N₄+N₅ =

Answer:

Explanation:

$N_{1}=^{5}C_{k}\times^{4}C_{5-k}$

  $N_{1}=5\times1$

$N_{2}=10\times4$

$N_{3}=10\times6$

$N_{4}=5\times4$

$N_{5}=1$

N₁+N₂+N₃+N₄+N₅ =126