GMAT Official Guide Quantitative Review 2019_ Book

4.5 b:、r ,,olv Answer Explanations

PSll 738

80. Half of a large pizza is cut into 4 equal-sized pieces, and
    the other half is cut into 6 equal-sized pieces. If a person
    were to eat 1 of the larger pieces and 2 of the smaller
    pieces, what fraction of the pizza would remain uneaten?

(A)

(B)

(C)

(D)

(E)

5-1213-247-122-317-24

Arithmetic ·、...�. �y --�:�--

Each of the 4 equal-sized pieces represents - of^1

8

th e w o e h 1· pizza smce each slice. 1s - of - of the^1 1

4 2

pizza. Each of the 6 equal-sized pieces represents

—^1 of the whole pizza since each slice is - of^1 -^1

12 6 2

of the pizza. The fraction of the pizza remaining

after a person eats one of the larger pieces and

2 of the smaller pieces is 1 -[½+ 2

(卢）］＝

1-(丛1.)=1-三= 1 - 工卫

8 6 48 24 24·

1h e correct answer 1s E.

PS14293

81. If a = 1 + -^1 +—1 1 +—and b = l + -a, then^1 what 1s
    4 16 64 4
    the value of a - b?

Arithmetic ,,_, ti,\n

Given that a = l + -^1 +—^1 +—^1 , it follows that

4 16 64

• 1 1 1 1 a=—+—+—+-^1 and sob=
  4 4 16 64 256
  1 +-^1 +—1 1 +-+—^1 .Then a-b=
  4 16 64 256

(^1 +巨二）-(1+且丛上十

1

)=

4 16 64 4 16 64 256

1

256

Th e correct answer ts B.

PSIOl 74

82. In a certain learning experiment, each participant had

three trials and was assigned, for each trial, a score of

either -2, -1, 0, 1, or 2. The participant's final score

consisted of the sum of the first trial score, 2 times the

second trial score, and 3 times the third trial score. If

Anne received scores of 1 and -1 for her first two

trials, not necessarily in that order, which of the

following could NOT be her final score?

(A) -4

(B) -2

(Cl^1

(D) 5

(E) 6

Arithmetic

If x represents Anne's score on the third trial, then

Anne's final score is either 1 + 2(-1) + 3x = 3x - l

or - (^1) + 2( 1 ) + 3x = 3x + l, where x can have the
value -2, -1, 0, 1, or 2. The following table shows
Anne's final score for each possible value of x.
(A)
(B)
(C)
(D)
(El
8
5

2

5

6

l-

2

5

6

1

-41

2

5-

2

5

6

1

6

9

• 2

5

6

/ X 3x-1 3x+ 1

• 2 - 7 - 5


• 1 - 4 -2
  。 - 1 1
  1 2 4
  "-^2 5 7
  Among the answer choices, the only one
  not found in the table is 6.

1h e correct answer 1s E.