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

1 2 Practice Tests for the SAT
Practice Test Seven Answers and Explanations 663
I
the answer choices may not be in the same form as your
original answer, so be prepared to simplify.
Getting to the Answer:
3
14. A
f(3) = 3- 3 + 3 2
= + v'33
3
= 2j + V27
= 2j + 3 \13
=-1+ 27(3 \/3 )
Difficulty: Medium
27 27
1 +81(
27
\/3 )
Strategic Advice: This question tells us that we have three
numbers in a sequence; to get the next term, we add a
constant, x. This means we have a set of evenly spaced
numbers, which means our average is equal to the median.
Getting to the Answer:
To answer this question, we must determine how to express
our median, s, in terms of r and x. Since we know each term
is equal to the previous term plus x, s = r + x, or (A).
15. D
Difficulty: Medium
Strategic Advice: You use different mental skills, such as
mechanical, conceptual, or creative, in different questions.
Ask yourself what particular skill(s) a question appears to
test; doing so will help you bring the proper kind of focus to
a question. This question, for example, almost exclusively
challenges your ability to translate from English into math.
Getting to the Answer:
Follow directions:
"Subtract 6 from x' means x - 6.
"Divide this sum by 3" means x; 6.
"Add 4 to this quotient" means
x; 6 + 4.
Then merely simplify:
x-6
3 +.!l=x+6
3 3
16. c
Difficulty: High
Strategic Advice: This question is so brief, yet so potentially
challenging. The best way to approach it is to distinguish the
separate ideas that it brings into play.
Getting to the Answer:
Begin by thinking about cubes of integers.
1 3 = 1
2 3 = 8
3 3 =27
... and so on. The term 25a is such a cube. So what you're
really asked here is how much farther must you continue the
list of cubes before you get to a number that 25 goes into?
Is 25 a factor of 4 3 , or 64? No.
Is 25 a factor of 5 3 , or 125? Yes; 25 goes into 125 five
times, so the minimum number a can be is 5.
SECTION 9
1. E
Difficulty: Low
Look for the most concise answer that does not introduce
any additional errors.
As written, this sentence is awkward and unnecessarily
wordy; (E) corrects this. Choices (B) and (D) use incorrect
grammatical structure; additionally, (D) is even wordier
than the original. Choice (C) introduces a verb tense that is
inappropriate in context.
2. E
Difficulty: Medium
Make sure that comparisons are structured to compare
logical things. Here, children are being compared to the
1960s. Choice (E) makes the comparison between children
in the two eras. Choice (B) does not address the error.
Choice (C) uses a singular pronoun, that, to refer to the
plural children. Choice (D) is idiomatically incorrect usage in
context.