crackthetest wrote:How to know if you need to use the permutation here, so that order really matters. I see the question just asks for one boy & 2 girls but not how they are arranged.
Pl. clarify.
Since the question doesn't mention a specific order, all orders are acceptable. Since all orders are acceptable, we have to take them all into account.
Identifying this as a pseudo-coin flip question makes life much easier, especially if you know the coin flip formula:
Prob(k results out of n flips) = (nCk)/2^n
In this question, we want 2 boys out of 3 kids, so let's let n=3 and k=2:
(3!/2!1!)/(2^3) = 3/8
Note that we could have looked at the question from the other side: we want 1 girl out of 3 kids, so let's let n=3 and k=1:
(3!/1!2!)/(2^3) = 3/8
Any question with a 50/50 probability can be solved using the above formula.
For more info about coin flip and pseudo-coin flip questions, check out this thread:
https://www.beatthegmat.com/coin-flip-qu ... 17911.html
