The problem is asking how much each person will need to pay. Simplifying the problem into an equation with variables (an algorithm) will greatly help you solve it:
S = Sales Tax = $ 7.18 per any purchase
A = Admission Ticket = $ 22.50 entry price for one person (no tax applied)
F = Food = $ 35.50 purchases for two people
We know the cost for one person was: (22.50) + [(35.50/2) + 7.18] =
$ 47.43 per person. Now we can check each method and see which one is the correct algorithm:
Method A)
[2A + (F + 2S)] / 2 = [ (2)(22.50) + [35.50 + (2)(7.18)] ]/ 2 = $47.43
Method A is the correct answer
Method B)
[(2A + (1/2)F + 2S) /2 = [(2)(22.50) + 35.50(1/2) + (2)7.18] / 2 = $38.55
Wrong answer. This method is incorrect because the tax for both tickets bought are not being used in the equation.
Method C)
[(A + F) / 2 ]+ S = [(22.50 + 35.50) / 2 ] + 7.18 = $35.93
Wrong answer. Incorrect Method. The food cost is being reduced to the cost of one person but admission price is set for two people.
A. The number of fabric-pattern-color combinations is 4 * 13 * 9 = 468
B. P(1st choice) = no of novels / total books = 3/6 = 1/2
P(2nd choice) = no of remaining novels/ total remaining books = 2/5
P(both novels) = 1/2 * 2/5 = 1/5 (without replacement assumed)
C. P(1st choice) = no of biographies / total books = 2/6 = 1/3
P(2nd choice) = no of remaining biographies/ total remaining books = 1/5
P(both biographies) = 1/3 * 1/5 = 1/15 (without replacement assumed)
D. P(1st choice) = no of history books / total books = 1/6
P(2nd choice) = no of novels/ total remaining books = 3/5
P(a history, then a novel) = 1/6 * 3/5 = 1/10 (without replacement assumed)
= -10x^2 - 6xy + 6xz
hope it helps
