A photographic negative is 3 cm by 2 cm. A similar print from the negative is 9cm long on its shorter side. What is the length o
f the longer side?
1 answer:
You might be interested in
Answer:
Step-by-step explanation:
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.
⇒
⇒
⇒
⇒
⇒
∴ Number of ways to select 3 books from 13 books for adoption is 286 .