SOLUTION: Picnic Misery Twenty boys went on a picnic. 5 got sunburned, 8 got bitten by mosquitoes, and 10 got home without mishap. What is the probability that a bitten boy was also burne

Of 20 boys, 10 got home without mishap.


Hence, 20-10 = 10 were misshaped.


So, we write

    10 misshaped = 5 sunburned + 8 bitten by mosquitoes - x counted twice.


It implies

    x counted twice = 5 + 8 - 10 = 3.


Thus 3 boys were sunburned -AND- bitten by mosquitoes.


Hence, of 8 bitten boys, 3 were also burned.


Then the probability that a bitten boy was also burned is   = 0.375.       ANSWER