Williams Tennis Fault
Probability Question?
In the 2004 Wimbledon tennis championship, Serena Williams made 63% of her first serves. When she faulted on her first serve, she made 93% of her second serves. Assuming these are typical of her serving performance, when she serves, what is the probability that she makes a double-fault?
This will be simple once it is explained out 
. First to explain what is known:
63% of first serve is hit
93% of second serve is hit
So basically, 63/100 times she hits the first serve and 93/100 times she hits the second serve. Now take the probability of not hitting the serve:
37% of the first serve is missed
7% of the second serve is missed
Therefore, 37/100 times she misses the first serve, and 7/100 times she misses the second serve.
To find probability, simple multiply the possible outcomes together. In this case, you want to find the probability of a miss for both serves (a double-fault). Therefore you would take:
37/100 • 7/100 = 2.59% probability of a double fault
Hope this helps 
