Hello, BiGpO6790!

It's a bit tricky . . . I wouldn't call it "basic".

A box contains: four 40w bulbs, five 60w bulbs, six 75w bulbs.

If bulbs are selected one by one in random order (without replacement),

what is the probability that at least two bulbs must be drawn to obtain a 75w bulb?

If a problem asks for "at least" or "at most",

. . it is often easier to consider theprobability.opposite

The opposite of "two or more drawn to get a 75w bulb"

. . is: "less than two drawn to get a 75w bulb."

Hence: .

Therefore: .

Someone check my reasoning and my math . . .please!