#### Answer

$\frac{3}{10}$

#### Work Step by Step

If the odds in favor of event E are a to b, then the probability of the event is
given by
P(E) = $\frac{a}{a+b}$
If you are given odds of 3 to 7 in favor of winning a bet, the probability of winning the bet is:
P(E) = $\frac{3}{3+7}$ = $\frac{3}{10}$