Bunuel
A rental firm has only two distinct types of vehicles: minivans and sedans. Each vehicle runs on exactly one fuel type, either gasoline or electricity. If a vehicle is selected at random, is the probability that it is a sedan running on electricity greater than the probability that it is a minivan running on gasoline?
(1) The probability that a randomly selected vehicle is either a minivan or runs on gasoline is 2/5.
(2) The probability that a randomly selected vehicle is either a sedan or runs on electricity is 5/8.
Let
Minivans = M
Sedans = S
Gasoline = G
Electric = E
We need to find out if
P(SE) > P(MG)
or
P(S∩E) - P(M∩G)
(1) The probability that a randomly selected vehicle is either a minivan or runs on gasoline is 2/5.
P(MUG) = 2/5
=> P(MUG) = P(M) + P(G) - P(M∩G) 2/5 = P(M) + P(G) - P(M∩G)
OR
via 2 x 2 matrix => 2/5 = P(ME) + P(MG) + P(SG)
Insufficient(2) The probability that a randomly selected vehicle is either a sedan or runs on electricity is 5/8.
P(SUE) = 5/8
=> P(SUE) = P(S) + P(E) - P(S∩E)
=> 5/8 = P(S) + P(E) - P(S∩E)
OR
via 2 x 2 matrix=> 5/8 = P(SE) + P(ME) + P(SG)
InsufficientCombining statement 1 and 2 we get
Type I - Probability equationsWe need to find if S∩E > M∩G?
2/5 = P(M) + P(G) - P(M∩G)
5/8 = P(S) + P(E) - P(S∩E)
Now P(M∩G) = 1 - P(SUE) = 1 - 5/8 = 3/8
Now P(S∩E) = 1 - P(MUG) = 1 - 2/5 = 3/5
=> 9/40 = P(S∩E) - P(M∩G) Hence, we can confirm that P(S∩E) > P(M∩G)
Sufficient
Type II - 2 x 2 matrixWe have
5/8 = P(SE) + P(ME) + P(SG)
2/5 = P(MG) - P(ME) - P(SG)
Subtracting
=> 9/40 = P(SE) + P(ME) + P(SG) - P(MG) - P(ME) - P(SG)
=> 9/40 = P(SE) - P(MG)
SufficientIMHO Option C