Question

Use Pascal’s Triangle to determine the probability that you will get three red lights (order does not matter) when looking at a row of five lights. Assume red and green are equally likely occurrences.

Answer 1

hte probability of "red red red green green" is \(\frac12\frac12\frac12\frac12\frac12=(\frac12)^5 =: p\).
Now count in how many situations there can be 3 red and 2 greens, in a 5 element-row.