Question

Suppose that three bulbs are randomly selected. What is the probability that exactly
two of the selected bulbs are rated 75 W?
ii. If two bulbs are randomly selected from the box of lightbulbs and at least one of them
is found to be rated 75 W, what is the probability that both of them are 75-W bulbs?
iii. Given that at least one of the two selected is not rated 75 W, what is the probability
that both selected bulbs have the same rating?

Answer 1

Answer:

i) $\frac{2}{3}$

ii) $\frac{1}{2}$

iii) $\frac{1}{2}$

Step-by-step explanation:

i) Number of bulbs rated by 75W = 2

  Total number of bulbs = 3

  Probability = $\frac{Number of favorable outcomes}{Total number of outcomes}$

                      = $\frac{2}{3}$                      

ii) Number of bulbs to be found of 75W = 1

   Total number of bulbs = 2

   Probability = $\frac{Number of favorable outcomes}{Total number of outcomes}$

                      = $\frac{1}{2}$

iii) Number of bulbs that is not rated = 1

   Total number of bulbs = 2

   Probability = $\frac{Number of favorable outcomes}{Total number of outcomes}$

                      = $\frac{1}{2}$