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Monique wants to check out as many books by her favorite author as possible. She can check out 3 books at a time from her library, where there are 6 books available written by her favorite author.
How many different sets of 3 of these books can Monique choose?

Monique wants to check out as many books by her favorite author as possible. She can check out 33 books at a time from her library, where there are 66 books available written by her favorite author.\newlineHow many different sets of 33 of these books can Monique choose?

Full solution

Q. Monique wants to check out as many books by her favorite author as possible. She can check out 33 books at a time from her library, where there are 66 books available written by her favorite author.\newlineHow many different sets of 33 of these books can Monique choose?
  1. Problem Understanding: Understand the problem and determine the formula to use.\newlineMonique wants to choose 33 books out of 66. This is a combination problem because the order in which she picks the books does not matter. The formula for combinations is C(n,k)=n!k!(nk)!C(n, k) = \frac{n!}{k!(n-k)!}, where nn is the total number of items to choose from, kk is the number of items to choose, and "!!" denotes factorial.
  2. Applying Combination Formula: Apply the combination formula to the problem.\newlineUsing the formula C(n,k)=n!k!(nk)!C(n, k) = \frac{n!}{k!(n-k)!}, we substitute nn with 66 (the total number of books) and kk with 33 (the number of books Monique wants to check out).\newlineC(6,3)=6!3!(63)!=6!3!3!C(6, 3) = \frac{6!}{3!(6-3)!} = \frac{6!}{3!3!}.
  3. Calculating Factorials: Calculate the factorials and simplify the expression.\newline6!=6×5×4×3×2×1=7206! = 6 \times 5 \times 4 \times 3 \times 2 \times 1 = 720,\newline3!=3×2×1=63! = 3 \times 2 \times 1 = 6.\newlineNow, we simplify the expression:\newlineC(6,3)=720(6×6)=72036=20C(6, 3) = \frac{720}{(6 \times 6)} = \frac{720}{36} = 20.
  4. Solution Conclusion: Conclude the solution.\newlineMonique can choose 2020 different sets of 33 books from the 66 books available by her favorite author.

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