5 pairs of footwears are to selected out of 4 pairs of shoes and 6 pairs of sandals. In how many ways this can be done if there should be at least 3 pairs of shoes?
5 pairs of footwears are to selected out of 4 pairs of shoes and 6 pairs of sandals. In how many ways this can be done if there should be at least 3 pairs of shoes? Correct Answer 66
GIVEN:
5 pairs of footwears are to selected out of 4 pairs of shoes and 6 pairs of sandals.
CONCEPT:
Basic concept of Permutation and combination.
Number of ways to select ‘a’ out of ‘b’ = bCa
CALCULATION:
There are 4 pairs of shoes and 6 pairs of sandals.
5 pairs of footwear is to selected such that there should be at least 3 pairs of shoes.
There are 2 possible cases:
3 pairs of shoes and 2 pairs of sandals + 4 pairs of shoes and 1 pairs of sandals
∴ Total number of ways = 4C3 × 6C2 + 4C4 × 6C1
⇒ 4 × 15 + 1 × 6
⇒ 66
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Feb 20, 2025