QUESTION IMAGE
Question
permutation or combination?
directions: recall that a permutation is an arrangement with a specific order, while a combination is a group with no specific order. determine whether the example represents a permutation or combination, then solve.
| example | p or c? | work solution and answer |
|---|---|---|
| 2) how many ways can 13 students line up for lunch? | ||
| 3) how many ways can you make a 3 - letter arrangements out of the letters in the word trapezoid. | ||
| 4) how many ways can you choose 2 books from a shelf of 40 books? | ||
| 5) how many ways can 12 swimmers finish in first, second, and third place? | ||
| 6) how many ways can mrs. sullivan choose two students from 27 to help put away calculators at the end of class? | ||
| 7) how many different 12 - letter arrangements can be made using the letters in the word indianapolis? | ||
| 8) how many different 11 - letter arrangements can be made using the letters in the word firecracker? | ||
| 9) there are 18 offensive players on the hockey team. how many ways can the coach choose a left wing, center, and right wing to start the game? |
Problem 1:
Step1: Identify P or C
Choosing candy bars, order doesn't matter, so combination (C).
Step2: Apply combination formula
The formula for combinations is \( _nC_r=\frac{n!}{r!(n - r)!} \), where \( n = 30 \), \( r=4 \).
\( _{30}C_4=\frac{30!}{4!(30 - 4)!}=\frac{30!}{4!×26!}=\frac{30×29×28×27}{4×3×2×1} \)
Step3: Calculate the value
\( \frac{30×29×28×27}{24}=\frac{30×29×28×27}{24}=27405 \)
Step1: Identify P or C
Lining up students, order matters, so permutation (P).
Step2: Apply permutation formula
The formula for permutations is \( _nP_r=\frac{n!}{(n - r)!} \), where \( n = 13 \), \( r = 13 \) (since we are lining up all 13 students).
\( _{13}P_{13}=\frac{13!}{(13 - 13)!}=\frac{13!}{0!}=13! \)
Step3: Calculate the value
\( 13!=13×12×11×\cdots×1 = 6227020800 \)
Step1: Identify P or C
Making letter arrangements, order matters, so permutation (P). First, find the number of distinct letters in "TRAPEZOID". The word "TRAPEZOID" has 9 distinct letters (T, R, A, P, E, Z, O, I, D). We are making 3 - letter arrangements, so \( n = 9 \), \( r=3 \).
Step2: Apply permutation formula
Using \( _nP_r=\frac{n!}{(n - r)!} \), with \( n = 9 \), \( r = 3 \).
\( _{9}P_{3}=\frac{9!}{(9 - 3)!}=\frac{9!}{6!}=9×8×7 \)
Step3: Calculate the value
\( 9×8×7 = 504 \)
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P or C? : C; Number of ways: \( 27405 \)