Number of ways to select 3 books from 13 books for adoption is 286 .
<u>Step-by-step explanation:</u>
A Permutation is an ordered Combination. When the order does matter it is a Permutation. There are basically two types of permutation:
- Repetition is Allowed: such as the lock above. It could be "333".
- No Repetition: for example the first three people in a running race. You can't be first and second.
Formula is given by:
, where n is the number of things to choose from, and we choose r of them, no repetitions, order matters. Here , n=13 , r=3.
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∴ Number of ways to select 3 books from 13 books for adoption is 286 .
-2<x<3 | *2
-4<2x<6 | +7
3< 2x+7< 13
3<10<13
The answer is C
The answer is 515. Because 5×103 is 515
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