In 1989 the price of a new model $S$ car was $x$ dollars

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VJesus12: Legendary Member; Posts: 2276; Joined: Sat Oct 14, 2017 6:10 am; Followed by:3 members

In 1989 the price of a new model $S$ car was $x$ dollars

by VJesus12 » Sat Nov 23, 2019 2:30 am

In 1989 the price of a new model $S$ car was $x$ dollars. If the price of the model $S$ car increased each year by 10 percent of the previous year's price, what was the price of the car, in dollars, in 1991 ?

(A) $1.10x$
(B) $1.20x$
(C) $1.21x$
(D) $1.25x$
(E) $1.33x$

[spoiler]OA=C[/spoiler]

Source: GMAT Paper Tests

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Source: Beat The GMAT — Problem Solving | Sat Nov 23, 2019 2:30 am

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by Brent@GMATPrepNow » Sat Nov 23, 2019 8:09 am

VJesus12 wrote:In 1989 the price of a new model $S$ car was $x$ dollars. If the price of the model $S$ car increased each year by 10 percent of the previous year's price, what was the price of the car, in dollars, in 1991 ?

(A) $1.10x$
(B) $1.20x$
(C) $1.21x$
(D) $1.25x$
(E) $1.33x$

KEY CONCEPT: Increasing a value by 10% is the same as multiplying that value by 1.1

We get:
Price in 1989 = x
Price in 1990 = (1.1)(x)
Price in 1991 = (1.1)(1.1)(x) = 1.21x

Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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by [email protected] » Sat Nov 23, 2019 9:51 am

Hi VJesus12,

We're told that in 1989 the price of a new model S car was X dollars and that the price of the car increased each year by 10 percent of the previous year's price. We're asked for the price of the car, in dollars, in 1991. This question can be solved in a couple of different ways, including by TESTing VALUES.

IF... the price of the car in 1989 was $100....
then the price of the car in 1990 was ($100) + (.1)($100) = $100 + $10 = $110
and the price of the car in 1991 was ($110) + (.1)($110) = $110 + $11 = $121

Thus, we're looking for an answer that equals $121, when X = 100. There's only one answer that matches...

Final Answer: [spoiler=]C[/spoiler]

GMAT assassins aren't born, they're made,
Rich

Contact Rich at [email protected]

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8086; Joined: Sat Apr 25, 2015 10:56 am; Location: Los Angeles, CA; Thanked: 43 times; Followed by:29 members

by Scott@TargetTestPrep » Thu Nov 28, 2019 4:24 pm

VJesus12 wrote:In 1989 the price of a new model $S$ car was $x$ dollars. If the price of the model $S$ car increased each year by 10 percent of the previous year's price, what was the price of the car, in dollars, in 1991 ?

(A) $1.10x$
(B) $1.20x$
(C) $1.21x$
(D) $1.25x$
(E) $1.33x$

[spoiler]OA=C[/spoiler]

Source: GMAT Paper Tests

The price of the model S car in 1991, in dollars, was:

x * 1.1 * 1.1 = 1.21x

Answer: C

Scott Woodbury-Stewart
Founder and CEO
[email protected]