combination

[thakurabhishek2529]

In case of probabilty questions---

when we look out for conditions ,say to get five heads out of seven toss ,why we calculate it as 5 choose 7 but not as 5 choose 14. Because basically we are selecting 5 out of 14 choices ,that is 7 heads and 7 tails?

[StaceyKoprince]

Please remember to read (and follow!) the forum guidelines before posting.

This folder is only for general strategy questions, not content or specific test problems. Check out the content / problem folders and post in the relevant folder depending upon the source of the problem you want to post (and make sure to follow the rules about banned sources). If you are a course student, you can also ask about other problems or issues before or after class or during section.

In this case, your question belongs in the General Math folder. I'll give a brief answer here, but if you want to discuss further, please post your question in the General Math folder.

The toss of a coin = 1 choice, not two. There are two possible outcomes (heads OR tails), but only one "choice" because only one outcome is possible at a time - it's one or the other.

So 7 tosses of a coin = 7 choices (each of which could be either heads or tails).