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

12 Practice Tests for t h e SAT I
Practice Test Four Answers and Explanations
381
SECTION 4
1. E
Difficulty: Low
Strategic Advice: Try rewriting t h e equation to make b ot
sides l ook l h
i ke eac h ot h er. Look for w h at num b er you can
p l ug in to t e l eft side to get t h e same t h ing on t h e rig h t
side-you s h ou ld n't h ave to do any actua l a l ge b ra.
Getting to the Answer:
If x were 7, t h en you'd h ave t + 7 on t h e l eft side as we ll .
2. D
Difficulty: Low
Strategic Advice: Use t h e Pyt h agorean t h eorem to find a.
Getting to the Answer:
22 + a2 = 5 2
3. A
Difficulty: Low
a2=21
a= v21
Strategic Advice: You want t h e num b er at fits t h e
conditions (divisi b l e b y 4 an d 6)
b ut not t h e conc l usion
(divisi b l e b y 8).
Getting to the Answer:
Divisi b l e b y 4 Divisi bl e b y 6 Divisi b l e b y 8
12 y y N
24 y y y
32 y N y
40 y N y
48 y y y
On l y 12 fits w h at we're l ooking for.
4. c
Difficulty: Medium
Strategic Advice: If you can't remem b er t h e area of a
para ll e l ogram (w h ic h is t h e same for any quadri l atera
wit h two sets of congruent sides), use t h e area of t h e
l
bpara ll e l ogram to guess t h e area of t h e circ l e, w h ic h l ooks to
e a b out h a lf t h at of t h e para ll e l ogram.
Getting to the Answer:
Area of para ll e l ogram= b x h = 14 x h 168 = 12
T h e h eig h t of t h e para ll e l ogram is a l so t h e diameter of t h e
circ l e, so r = 6.
Area of circ l e= w2 = 367t
5. E
Difficulty: Medium
Strategic Advice: If t h e first num b er is even, t h en w h at do
you know a b out t h e product? If t h e first num b er is odd, t h en
w h at h as to h appen for t h e product to b e even?
Getting to the Answer:
If t h e first num b er is even, t h en t h e product wi ll a l ways b e
even. T h ere are 3 even num b ers on t h e first spin, and t h en
6 num b ers on t h e second spin, so t h is is a tota l of 3 x 6 =
18 possi b i l ities.
If t h e first num b er is not even (w h ic h can h appen 3 ways),
t h e second num b er must b e even (w h ic h can h appen 3
ways), so t h is is a tota l of 3 x 3 = 9 possi b i l ities.
So t h e tota l num b er of positive products is 9+18 = 27.
Since we h ave 6 num b ers on t h e first spin and 6 num b ers
on t h e second spin, t h ere are 6 x 6 = 36 possi b i l ities
overall, so the probability of an even product is ·
6. D
Difficulty: Medium
Strategic Advice: Remem b er t h at direct l y proportiona l means
a= kb (or F = k) and inverse l y proportiona l means ab= k.
Getting to the Answer:
We want t h e points w h ere ab a l ways turns out to b e t h e
same num b er. T h is is on l y true in (D).
7. c
Difficulty: Medium
Strategic Advice: T h is is a perfect c h ance for you to Pick
Num b ers.
Getting to the Answer:
LetA = -1.5
LetB = 0.5
Ax B = -1.5 x 0.5 = -0.75
From t h e answer c h oices given, on l y X cou ld b e -0.75.