Of the 20 members of a kitchen crew, 17 can use the meat-cutting machine, 18 can use the bread-slicing machine, and 15 can use both machines. If one member is chosen at random, what is the probability that the member chosen will be someone who cannot use either machine? Choose the correct choice from the following options
A) 0  B) 1/10  C) 1/7  D) 1/4  E) 1/3
You know how to solve for Total number of people who can use at least one machine:   Total = n(A) + n(B) - n(A and B)   Total people who can use at least one machine = 17 + 18 - 15= 
<gadget id="calculator">17 + 18 - 15</gadget>
<output>20</output>
20   So all 20 people know how to use at least one machine. Hence, if you pick anyone, the probability is 0 that he wouldn't know how to use any machine.   0nswer 0
<result>A</result>
Of the 20 members of a kitchen crew, 17 can use the meat-cutting machine, 18 can use the bread-slicing machine, and 15 can use both machines. If one member is chosen at random, what is the probability that the member chosen will be someone who cannot use either machine?