It is currently 22 Oct 2017, 23:25

### GMAT Club Daily Prep

#### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# If the radius of a circle is increased by 10%, by how much

Author Message
Senior Manager
Joined: 02 Oct 2005
Posts: 297

Kudos [?]: 24 [0], given: 0

If the radius of a circle is increased by 10%, by how much  [#permalink]

### Show Tags

23 Oct 2005, 12:58
00:00

Difficulty:

(N/A)

Question Stats:

100% (00:02) correct 0% (00:00) wrong based on 1 sessions

### HideShow timer Statistics

This topic is locked. If you want to discuss this question please re-post it in the respective forum.

If the radius of a circle is increased by 10%, by how much
is its area increased?

A. 25%
B. 21%
C. 20%
D. 15%
E. 10%

Kudos [?]: 24 [0], given: 0

Manager
Joined: 04 Oct 2005
Posts: 246

Kudos [?]: 86 [0], given: 0

### Show Tags

23 Oct 2005, 13:03
Area of circle A = pi*r^2

increase r by 10%
new area is: pi*(1.1r)^2 = 1.21*pi*r^2

thus area is increased by 21%

Kudos [?]: 86 [0], given: 0

Senior Manager
Joined: 02 Oct 2005
Posts: 297

Kudos [?]: 24 [0], given: 0

### Show Tags

23 Oct 2005, 16:51
OA is B and here is the explanation:

The formula for the radius of the original circle is

The formula for the new radius is

Thus, the area of the circle is increased by 21%.

Kudos [?]: 24 [0], given: 0

23 Oct 2005, 16:51
Display posts from previous: Sort by