GMAT® Official Guide 2019 Quantitative Review
Using (1) and (2) together, the two equations can
be solved simultaneously for x and y. One way
to do this is by adding the two equations,
x + y = 10 and x -y = 6, to get 2x = 16, or x = 8.
Then substitute into either of the equations to
obtain an equation that can be solved to get
y = 2. Thus, xy can be determined to have the
value (8)(2) = 16. Alternatively, the two equations
correspond to a pair of nonparallel lines in the
(x,y) coordinate plane, which have a unique point
mcommon.The correct answer is C;
both statements together are sufficient.
DS13189- If n is the least of three different integers greater than
1, what is the value of n?
(1) The product of the three integers is 90.
(2) One of the integers is twice one of the other two
integers.Arithmetic
Given that n is the least of three different integers
n, p, and q, where 1 < n < p < q, determine the
value of n.(1) This indicates that the product of the three
integers is 90. The integers could be 2, 5,
and 9 since (2)(5)(9) = 90, and n would be- However, the integers could be 3, 5, and
6 since (3)(5)(6) = 90, and n would be 3;
NOT sufficient.
(2) This indicates that one of the integers is
twice one of the others. It could be that
p = 2n, or q = 2n, or q = 2p. For example, if
n = 2,p = 4, and q = 5, then p = 2n, and the
value of n would be 2. If n = 3,p = 4, and
q = 6, then q = 2n, and the value of n would
be 3; NOT sufficient.
Taking (1) and (2) together, if p = 2n, then npq =
(n)(2n)(q) = 90, or n^2 q = 45. It follows that n =
3,p = (2)(3) = 6, and q = 5. The value of n is 3. If
q = 2n, then npq = (n)(p)(2n) = 90 or n^2 p = 45. It
follows that n = 3,p = 5, and q = (2)(3) = 6. The
value of n is 3. If q = 2p, then npq = (n)(p)(2p) =
90 or np^2 = 45. It follows that n = 5,p = 3, and
q = (2)(3) = 6, and this case can be eliminated
because n is not the least of the three integers.
Therefore, the value of n is 3.
Alternatively, taking (1) and (2) together, the
integers n,p, and q are among 2, 3, 5, 6, 9, 10, 15,
18, 30, and 45 since they are factors of 90 from
(1). Because all three integers are different and
90 = (2)(3)(15) = (2)(3^2 )(5), n,p, and q must be
among the integers 2, 3, 5, 9, 10, and 15. Only
two pairs of these integers satisfy (2): 3 and 6
since 6 = (2)(3) and 5 and 10 since 10 = (2)(5).
However, for each possible value for n, (n)(5)(10) >- Therefore, the only pair that satisfies both (1)
and (2) is 3 and 6, and the third integer is then
_.2Q__ = 5. Thus, the value of n is 3.
(3)( 6)
The corriect answer is C;
both statements together are sufficient.
DS16461- Is x^2 greater than x?
( 1) x^2 is greater than 1.
(2) x is greater than -1.Arithmetic; Algebra
(1) Given x2 > 1, it follows that either x > l or
x < -1. If x > l, then multiplying both sides
of the inequality by the positive number x
gives x2 > x. On the other hand, if x < -l,
then x is negative and x2 is positive
(because x2 > 1), which also gives x2 > x;
SUFFICIENT.
(2) Given x > -l, x2 can be greater than x (for
example, x = 2) and x2 can fail to be greater
than x (for example, x = O); NOT sufficient.
The correct answer is A;
statement 1 alone is sufficient.
DS03503- Michael arranged all his books in a bookcase with
10 books on each shelf and no books left over. After
Michael acquired 10 additional books, he arranged
all his books in a new bookcase with 12 books on
each shelf and no books left over. How many books
did Michael have before he acquired the 10 additional
books?
(1) Before Michael acquired the 10 additional books,
he had fewer than 96 books.
(2) Before Michael acquired the 10 additional books,
he had more than 24 books.