Could someone offer an explanation behind why we use 5C0, 5C1, and 5C2 for this binomial problem?
Why not simply 1 - 5C3? This one really threw me for a loop…
At least 3 days means 3, 4, or 5 days.
You can add up the probabilities for 3 days, 4 days, and 5 days, or you can add up the probabilities for 0 days, 1 day, and 2 days and subtract the sum from 1. Pretty much the same amount of work either way.
Becase the question is asking for P(x>=3) which is the same as P(X=3) + P(X=4) + P(X=5). 1 - 5C3 as suggested by you would give you the probabilitiy for all outcomes except x=3, meaning P(X=1) + P(X=2) + P(X=4) + P(X=5), which is different from what is asked.
Regards, Oscar
Fixed that for you.
Thank you, magician!
My pleasure.