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

12 Practice Tests for t h e SAT I
Practice Test Four Answers and Explanations
373
13. E
Difficulty: Medium
Strategic Advice: Find t h e pattern, t h en figure out h ow
often it repeats.
Getting to the Answer:
T h e first few terms of t h e series are 4, -4, -1, 1, 4, -4, -1,
1 ... , so t h e pattern repeats every 4 terms. Since 3 Z = 9 Rl,
it wi ll go t h roug h t h e cyc l e 9 times and end on t h e first
num b er of t h e cyc l e, w h ic h is 4.
14. A
Difficulty: Medium
Strategic Advice: Sketc h yourse l f a picture and l oo k for h ow
t h ey-intercept and s l ope c h ange.
Getting to the Answer:
y
3
x
From t h e diagram, you can see t h at m sti ll h as y-intercept 2,
b ut t h e s l ope now goes down 3 and over 1, w h ic h is -3. So
p l ugging into y = mx + b, t h e equation is y = -3x + 2.
15. D
Difficulty: Medium
Getting to the Answer:
Remem b er t h e formu l a for percent c h ange:
act.ua l c h ange x 1 OOO/o
origina l amount
From year 6 to year 9, t h e tree increased from 25 ft to 100 ft,
or 75 ft. T h is is i = gg = 300% of t h e h eig h t in year 6.
16. E
Difficulty: Medium
Strategic Advice: Find t h e vo l ume of t h e cy l inder in t h e
figure, t en find t h e vo l ume of eac h answer and compare.
Start wit h t h e formu l a t h at is easier to work wit h : t h e vo l ume
of a rectangu l ar so l id.
Getting to the Answer:
Vo l ume of cy l inder= rtr2h = 7t(m)2(2x) = 27t3x3
(D) Vo l ume of so l id= (2x) (m)(m) = 27t2x3
(E) Vo l ume of so l id= (2m)(m)(m) = 27t3x3
17. B
Difficulty: Medium
Strategic Advice: Don't so l ve for b! On Test Day, you wi
see questions t h at ask you to so l ve for expressions wit h ll
varia b l es, l i ke b + 1. T h ere's got to b e an easy way to factor
or rearrange t h e varia b l es in t h e equation in or der to so l ve
for b + 1.
Getting to the Answer:
Remem b er w h en you're so l ving for a varia b l e t h
h at you
ave to remove t h e stuff t h at's a dded and su b tracted first,
t h en get rid of w h at's mu l tiplied/divided. In ot h er words,
you need to move t h e 3a b efore you can worry a b out
t h e 3 in front of b + 1 .
3 (b + 1) = c -3a
(b + 1) = 3a = c -
3 3 -a
18. B
Difficulty: Hig h
Strategic Advice: Start wit h t h e easiest Roman numera l to
eva l uate. If you're a b l e to prove t h at Roman numera l true,
t h en e l iminate any answer c h oice t h at does not use t h at
Roman numera l .