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Amara needs to create a special tasting menu at her restaurant. She needs to select 4 dishes from 7 available dishes and put them in a tasty sequence.
How many unique ways are there to arrange 4 of the 7 dishes?

Amara needs to create a special tasting menu at her restaurant. She needs to select 44 dishes from 77 available dishes and put them in a tasty sequence.\newlineHow many unique ways are there to arrange 44 of the 77 dishes?

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Q. Amara needs to create a special tasting menu at her restaurant. She needs to select 44 dishes from 77 available dishes and put them in a tasty sequence.\newlineHow many unique ways are there to arrange 44 of the 77 dishes?
  1. Problem Understanding: Understand the problem.\newlineAmara needs to select 44 dishes out of 77 and arrange them in a sequence. This is a permutation problem because the order of the dishes matters.
  2. Permutation Formula: Apply the formula for permutations without repetition.\newlineThe number of ways to arrange kk items from a set of nn items is given by the formula n!(nk)!\frac{n!}{(n-k)!} where !"!" denotes factorial.\newlineHere, n=7n = 7 (total dishes) and k=4k = 4 (dishes to be arranged).
  3. Calculate n!n!: Calculate the factorial of nn (7!7!).\newline7!=7×6×5×4×3×2×17! = 7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1
  4. Calculate (nk)!(n-k)!: Calculate the factorial of (nk)(n-k) which is (74)!(7-4)! or 3!3!.3!=3×2×13! = 3 \times 2 \times 1
  5. Substitute into Formula: Substitute the values into the permutation formula.\newlineNumber of unique ways = 7!/(74)!7! / (7-4)!\newline= 7!/3!7! / 3!
  6. Perform Calculation: Perform the calculation.\newlineNumber of unique ways =(7×6×5×4×3×2×1)/(3×2×1)= (7 \times 6 \times 5 \times 4 \times 3 \times 2 \times 1) / (3 \times 2 \times 1)\newlineThe 3×2×13 \times 2 \times 1 in the denominator and numerator cancel each other out.\newlineNumber of unique ways =7×6×5×4= 7 \times 6 \times 5 \times 4\newline=840= 840

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