### Video Transcript

A bag contains seven white marbles,
eight black marbles, and seven red marbles. If a marble is chosen at random
from the bag, what is the probability that it is white?

We can recall that to find the
probability of an event occurring, we take the number of favorable outcomes and
divide it by the total number of outcomes. Here, we’re asked to calculate the
probability of getting a white marble. And we can write this as 𝑃
brackets 𝑊 for white. We then need to establish how many
white marbles there are. And we’re told that there are
seven. So this will be the value on the
numerator. The value on the denominator will
be the total number of marbles. So we’re told that there are seven
white, eight black, and seven red. So we add these values
together. This gives us the fraction seven
over 22. We can’t simplify this fraction any
further. So the probability of getting a
white marble is seven over 22.