In 1989 the price of a new model \(S\) car was \(x\) dollars

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

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

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