Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

geometric sequence [#permalink]
17 Dec 2011, 07:01

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

100% (00:00) correct
0% (00:00) wrong based on 5 sessions

v, w, x, y, z A geometric sequence is a sequence in which each term after the fi rst is equal to the product of the preceding term and a constant. If the list of numbers shown above is an geometric sequence, which of the following must also be a geometric sequence? I. 2v, 2w, 2x, 2y, 2z II. v + 2, w + 2, x + 2, y + 2, z + 2 III. \sqrt{v}, \sqrt{w}, \sqrt{x}, \sqrt{y}, \sqrt{z}

(A) I only (B) II only (C) III only (D) I and II (E) I and III

Re: geometric sequence [#permalink]
18 Dec 2011, 09:47

yeah, E is correct.

i) let's say orig sequence v, w, x, y, z = a, ba, b*ba, b*b*ba.. then 2v, 2w, 2x, 2y, 2z will be, 2a, 2ba, 2b*ba, 2*b*b*ba... every number is still a multiplication of the previous term by the constant - b

iii) again lets say v, w, x, y, z = a, ba, b*ba, b*b*ba.. then \sqrt{v}, \sqrt{w}, \sqrt{x}, \sqrt{y}, \sqrt{z} = \sqrt{a}, \sqrt{ba}, \sqrt{b*b*a}, \sqrt{b*b*ba}...

The first term in the sequence is now \sqrt{a}, and every term in the new sequence is still equal to the previous term multiplied by a constant - \sqrt{b}

Re: geometric sequence [#permalink]
19 Dec 2011, 02:10

my ans is E

lets say series is 2,4,8,16,32 where common multiple is 2 let us multiply each term by 3, new series becomes 6,12,24,48,96 which is again a GP whose common multiple is 2

same case applies for square root

while adding 2 to each term will not generate any GP

gmatclubot

Re: geometric sequence
[#permalink]
19 Dec 2011, 02:10