Example: Probability through counting outcomes | Precalculus | Khan Academy

The probability of getting exactly 2 heads when flipping three coins. Thinking about this by visualy depicting all of the outcomes.

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[getdroppedson]

An algebraic approach:
You can think of it as the amount of ways to permutate the letters H, H, T (two heads and one tail). There are 3! permutations but we know that for each permutation, the H's can be arranged in 2!= 2 ways. This means that each permutation occurs twice and thus we divide the number of permutations with 2: 3!/2 = 3 (thus there are 3 ways to get exactly 2 heads)
Furthermore, we can find the total number of possible outcomes by the operation 2*2*2 = 8 (the first coinflip has 2 possibilities, either H or T, and the same can be said about the remaining two coinflips).
Thus P= 3/8

[adityaguin]

Wouldn't you want to use a tree diagram in the beginning for understanding purposes?
Just a suggestion

[superdau]

IMO education in probability and statistics should be given priority before calculus or even trigonometry. Everybody always asks "what is this and that good for?" when learning math. Statistics has some of the most useful "daily" life applications.

[prerna]

Is there is an formula for finding the possible outcomes.. It very confusing

[sovietmaths]

You should probably do a tree diagram.