davidtrinh
New member
- Joined
- Dec 1, 2016
- Messages
- 10
(ex) A student has 7 different textbooks. How many different ways of selecting and arranging 4 books on a shelf are there?
my attempt
I do seven choose four to get 7C4 = 35. But, the answer key says 210.
How do you get the answer? Thanks a lot.
my attempt
I do seven choose four to get 7C4 = 35. But, the answer key says 210.
How do you get the answer? Thanks a lot.