A box contains six 40-W bulbs, five 60-W bulbs, and four 75-W bulbs. If bulbs are selected one by one in random order, what is the probability that at least two bulbs must be selected to obtain one that is rated 75 W?

Answer:- Given:

The number of bulbs =

The number of bulbs =

The number of bulbs =

To find:

P (At least   bulbs must be selected to obtain one that is rated  75w)

Step-by-step explanation:

Let us reflect as At least   bulbs must be certain to obtain one that is rated  75w

A1= Just one bulb was selected which is rated75w

Answer:

Consequently, the probability that at least   bulbs must be selected to obtain one that is rated   75w is 11/15