You have 20 different neckties in your wardrobe. How many

Gabriella Sellers

Gabriella Sellers

Answered question

2022-06-24

You have 20 different neckties in your wardrobe. How many combinations of three ties could you choose?

Answer & Explanation

Donavan Scott

Donavan Scott

Beginner2022-06-25Added 22 answers

Step 1
From the detailed question i picked the word Combinations
Which i should believe the question is gotten from the topic; Permutation and Combination..
Follow this simple steps..
You have 20 Neck ties, out of 3 ties could you choose..
It goes with this formula of combination;
Step 2
Combination Formula n C r = n ! ( n - r ) ! r !
Where n = 20 and r = 3
20 ! ( 20 - 3 ) ! 3 !
x 20 ! 17 ! 3 !
x 20 × 19 × 18 × 17 × 16 × 15 × ... ... . . × 3 × 2 × 1 ( 17 × 16 × 15 × ... . . × 3 × 2 × 1 ) × ( 3 × 2 × 1 )
x 20 × 19 × 18 × 17 × 16 × 15 × ... . . × 3 × 2 × 1 ( 17 × 16 × 15 × ... . . × 3 × 2 × 1 ) × ( 3 × 2 × 1 )
x 20 × 19 × 18 3 × 2 × 1
x 6840 6
x 1140 ways
Mayra Berry

Mayra Berry

Beginner2022-06-26Added 7 answers

Step 1
There will be:
20 different choices for the first tie and then
19 different choices for the second tie and then
18 different choices for the third tie.
This gives 6840 possibilities
However within these the same groups will be repeated.
Step 2
For example Red, Blue, Green, and Red, Green, Blue, and Blue,Red, Green are all the same combination of colours.
There are 3 × 2 × 1 = 6 ways of arranging three ties.
So the total number of possible combinations is 20 × 19 × 18 3 × 2 × 1 = 6840 6 = 1140

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