12.Practice.Tests.for.the.SAT_2015-2016_1128p

1 2 Practice Tests for the SAT
Practice Test Eight Answers and Explanations 737
I
15. 595
Difficulty: Medium
Strategic Advice: Problems like this are tricky because
there are so many steps to take before you find the answer.
Always make sure the answer is what the question is asking
for before you stop working.
Getting to the Answer:
Number of voters = 800/o(total union members):
(.80)(1,500) = 1,200
Number of voters who answered yes = 400/o(number who
voted):
(0.40)(1,200) = 480
Number of voters who didn't answer yes =
number who voted - number who voted yes:
1,200 - 480 = 720
Number of voters who answered no =
number who didn't answer yes - number who didn't
respond:
720 - 125 = 595
16. 92.5
Difficulty: Medium
Strategic Advice: Find the difference in costs between the
3-layer cake and the 6-layer cake. Then use that difference
to find the additional cost per layer.
Getting to the Answer:
85.00 - 62.50 = 22.50
22.50 _,_ 3 = 7.50 = cost per layer
So the cost for a 7-layer cake would be the cost of a 6-layer
cake plus an additional layer:
17. 25
85.00 + 7.50 = 92.5
Difficulty: Medium
Strategic Advice: This is an example of a percent increase
and/or decrease problem. Increasing 45 by P percent
means adding P percent of 45 to 45, so this results in 45 +
P
·
45P
(PO/o of 45), or 45 + 100
x 45, which equals 45 + 100
.
Decreasing 75 by P percent means taking P percent of 75
away from 75, so decreasing 75 by P percent results in 75 -
P
·
75P
(fYJ!o of 75) or 75 - 100
x 75, which equals 75 - 100
.
Getting to the Answer:
Increasing 45 by P percent gives the same result as
decreasing 75 by P percent, so you have the equation =
45 + jg:; = 75 - ig6. Now solve this equation for P.
Subtracting 45 from both sides results in jg:; = 30 - ig6.
Adding ig6 to both sides gives you \06 = 30. Multiplying
both sides by 1 OO
results in P = 1 00 x
30 = 1 00 x 30 .
120 120 120
Canceling a factor of 30 from the top and bottom gives you
1 O , which equals 25. So P = 25.
18. 60
Difficulty: High
Strategic Advice: For these logic problems, try making
a diagram if you are confused. Visualizing what you are
dealing with will often help to bring about the solution.
Getting to the Answer:
Solving this problem comes mainly from understanding it.
The man uses five different tile colors-let's call them R, B,
Y, G, and P for short. We can make a diagram of all of the
two-color combinations involved:
RB RY RG RP
BY BG BP
YG YP
GP
We see that there are 4 + 3 + 2 + 1 = 1 O possible tile
pairings. If each is used exactly 3 times, we have 10 x 3 =
30 pairs, and since each pair contains 2 tiles, there is a total
of 30 x 2 = 60 tiles used.