Bytelearn - cat image with glassesAI tutor

Welcome to Bytelearn!

Let’s check out your problem:

Luis is packing a bag for vacation. He has 9 unique shirts, but he can only fit 5 in his bag.
How many different groups of 5 shirts can he take?

◻

Luis is packing a bag for vacation. He has 99 unique shirts, but he can only fit 55 in his bag.\newlineHow many different groups of 55 shirts can he take?\newline

Full solution

Q. Luis is packing a bag for vacation. He has 99 unique shirts, but he can only fit 55 in his bag.\newlineHow many different groups of 55 shirts can he take?\newline
  1. Identify Problem: Luis has 99 unique shirts and wants to choose 55 for his bag. This is a combination problem, not permutation, since the order doesn't matter.
  2. Use Combination Formula: To calculate combinations, we use the formula: C(n,k)=n!k!(nk)!C(n, k) = \frac{n!}{k!(n-k)!}
  3. Substitute Values: Plug in the values: C(9,5)=9!5!(95)!C(9, 5) = \frac{9!}{5!(9-5)!}
  4. Simplify Denominator: Simplify the denominator: C(9,5)=9!(5!4!)C(9, 5) = \frac{9!}{(5!4!)}
  5. Calculate Factorials: Calculate the factorials: 9!=9×8×7×6×5!9! = 9\times8\times7\times6\times5!, 5!=5×4×3×2×15! = 5\times4\times3\times2\times1, and 4!=4×3×2×14! = 4\times3\times2\times1
  6. Cancel Common Factorial: Cancel out the common 5!5! in numerator and denominator: C(9,5)=9×8×7×64×3×2×1C(9, 5) = \frac{9\times8\times7\times6}{4\times3\times2\times1}
  7. Perform Calculation: Perform the calculation: C(9,5)=9×8×7×64×3×2×1=9×2×7×61=126C(9, 5) = \frac{9\times8\times7\times6}{4\times3\times2\times1} = \frac{9\times2\times7\times6}{1} = 126

More problems from Counting principle