This is because you have to start with the probability of each urn. The first urn has 13 total balls (5 white and 8 yellow). Since 5 of them are white, the odds of pulling a white ball are 5/13. Then find the same for the second urn (9 white and 2 yellow). Therefore there are 11 total balls and 9/11 chance of getting a white one. After finding both, multiply them together to get the answer.
A family has 8 girls and 4 boys. A total of 3 children must be chosen to speak on the behalf of the family at a local benefit. What is the probability that no girls and 3 boys will be chosen? D. 1/55.<span />