Two urns contain white balls and yellow balls. The first urn contains 3 white balls and 6 yellow balls and the second urn contains 7 white balls and 3 yellow balls. A ball is drawn at random from each urn. What is the probability that both balls are white?
The probability of drawing a white ball from the first urn is $\frac{3}{9}=\frac{1}{3}$. The probability of drawing a white ball from the second urn is $\frac{7}{10}=\frac{7}{10}$. Since the two events are independent, the probability of both events occurring is the product of their probabilities: $$\left(\frac{1}{3}\right)\left(\frac{7}{10}\right)=\boxed{\frac{7}{30}}.$$
