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

12 Practice Tests for the SAT
81 4 Practice Test Nine Answers and Explanations
Getting to the Answer:
Plug in the given value for b and see if the equation works.
If you start with (C), which is a good idea when Backsolving,
you're in luck here. If b were equal to 2, the equation 2a
+ Sb = 1 S would be 2a + 1 0 = 1 S, or 2a = S, or a= 2.5.
But you're given that a is an integer, so a cannot possibly be
2.5, so b= 2 doesn't work, and (C) is correct.
You might have noticed that in the equation 2a + Sb =
1 S you have an even number, 2a, plus another number,
Sb, being equal to an odd number, 1 S. An even number
plus an even number equals an even number, and an
even number plus an odd number equals an odd number,
so the expression Sb must be an odd number. If Sb is an
odd number, then b must be an odd number (since odd x
odd = odd and odd x even = even). Therefore, the correct
answer choice is the one even number, again (C).
14. B
Difficulty: Medium
Strategic Advice: Since you're given that y is between -1
and 0, why not pick an appropriate number for y and plug it
into each answer choice?
Getting to the Answer:
1
Try y= -·2"
(A) is y2 =(-
1) 2 =t
(B) is 1 - y = 1 - J_ = 1 J_
2 2
(C) is 1 + y = l + (-1 ) = 1
(D) is 2y = 2(-1) = -1
(E)
. l l l 2
IS y + 2 = ( - 1) + 2 =
i = 3
16. c
Difficulty: Medium
Strategic Advice: A good way to solve this question is by
making yourself a little table.
Getting to the Answer:
Each employee is described by two different things. Each
one is a woman or a man, and each one either drives to
work or takes public transportation. So make this table:
D
p
W
In this table, each box will contain the number of employees
having the two appropriate attributes. For example, the
box in the lower right corner is the number of men who
take public transportation. You can also put numbers in the
margins. For example, you can put the number of women
in the company below the box in the lower left corner. Now
begin to put numbers in the table from the information
in the question. The question tells you that there are 2S
women and 2S men and that 29 employees drive to work.
Each of these three pieces of information describes only
one attribute of the employees, so these numbers will go in
the appropriate margins. We're told that 6 men take public
transportation. This describes both attributes, so put a 6 in
the lower right box. Now your table should look like this:
W
M
M
Choice (B) is the greatest.
D
29
15. B
Difficulty: Medium
Strategic Advice: The union of two sets consists of all the
elements that appear in either set.
Getting to the Answer:
SetA contains S elements. Set B contains S elements, none of
which are in set A. Their union contains S + S = l O elements.
p
6
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