Answer
$P(first~ball~selected~is~on~the~Lingo~board)=\frac{5}{7}\approx0.7143$
Work Step by Step
The given Lingo Board has 15 numbers. So, there are 15 balls in the bin corresponding to each of the 15 numbers on the board. So, $N(number~ball)=15$
There are 3 prize balls: $N(prize~ball)=3$
There are 3 “stopper” balls: $N(stopper~ball)=3$
The sample space: all balls: $15+3+3=21$. So, $N(S)=21$
$P(first~ball~selected~is~on~the~Lingo~board)=\frac{N(number~ball)}{N(S)}=\frac{15}{21}=\frac{5}{7}\approx0.7143$
