GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 18 Oct 2019, 21:44 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  If O represents the center of a circular clock and the point of the cl

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:

Hide Tags

Math Expert V
Joined: 02 Sep 2009
Posts: 58453
If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

1
4 00:00

Difficulty:   95% (hard)

Question Stats: 37% (02:21) correct 63% (01:52) wrong based on 164 sessions

HideShow timer Statistics If O represents the center of a circular clock and the point of the clock hand is on the circumference of the circle, does the shaded sector of the clock represent more than 10 minutes?

(1) The clock hand has a length of 10.
(2) The area of the sector is more than $$16\pi$$.

Kudos for a correct solution.

Attachment: 2015-06-24_1004.png [ 15.92 KiB | Viewed 3124 times ]

_________________
Manager  Status: Perspiring
Joined: 15 Feb 2012
Posts: 82
Concentration: Marketing, Strategy
GPA: 3.6
WE: Engineering (Computer Software)
Re: If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

1
Concept : Wall clock is a circular area with 12 sectors of 5 minute each.
Therefore the area of 10 min sector = π*r*r*(2/12)

Considering statement 1:
Radius = 10, Area of circle = πr^2 = 100π
Area of 10 min sector = 100π*(2/12) = 16.66π.
But we don't know if the shaded area is more than 16.66π or less than that.
Hence Insufficient !

Considering statement 2:
Area is more than 16π. But we don't know the radius.
Hence Insufficient

Using 1 & 2 both:
Area of sector is more than 16π
But, if the area is 16.22π, then it is less than 10 mins & if it is more than 16.86π then it is more than 10 mins.

Hence E !!
CEO  D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2978
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

1
1
Bunuel wrote: If O represents the center of a circular clock and the point of the clock hand is on the circumference of the circle, does the shaded sector of the clock represent more than 10 minutes?

(1) The clock hand has a length of 10.
(2) The area of the sector is more than $$16\pi$$.

Kudos for a correct solution.

Attachment:
2015-06-24_1004.png

Total angle at the centre of the clock = 360
Total parts in which the angle 360 is divided equally = 12
Angle between any two adjacent numbers in clock (i.e. 1 gap) = 360/12 = 30 degree
Angular measurement of 10 minutes in a clock = Angle between two gaps = 30*2 = 60 degrees

Question REDEFINED : Does the shaded sector of the clock represent more than 60 degrees?

Statement 1: The clock hand has a length of 10

With Radius of the sector, we can't find the angle made by sector

Hence, NOT SUFFICIENT

Statement 2: The area of the sector is more than $$16\pi$$

Area of Sector > (Angle/360)*$$(/pi)r^2$$

But Radius of the sector is unknown, therefore, we can't find the angle made by sector

Hence, NOT SUFFICIENT

Combining the two statements

Area of Sector > $$16\pi$$
Area of Sector = (Angle/360)*$$(/pi)r^2$$
i.e. (Angle/360)*$$(/pi)r^2$$ > $$16\pi$$
i.e. (Angle) > $$16*360 / 10^2$$
i.e. (Angle) > $$57.6$$

i.e. Angle may or may not be Greater than 60 degrees

Hence, NOT SUFFICIENT

_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Manager  B
Joined: 26 Dec 2012
Posts: 144
Location: United States
Concentration: Technology, Social Entrepreneurship
WE: Information Technology (Computer Software)
Re: If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

A clock can be divided in 12 equal parts, to find out the shaded region more than 10 minutes or not, we need radios of the clock and angle made by the clock for that region.

A) Radius =10 , shaded region angle is not given so insufficient
B) Area if given but angle and radius is not known, so insufficient

Together A+B) we have radius and area of the sector, so we can find out the angle of the sector, so Sufficient

Hence answer is C
Thanks,
CEO  D
Status: GMATINSIGHT Tutor
Joined: 08 Jul 2010
Posts: 2978
Location: India
GMAT: INSIGHT
Schools: Darden '21
WE: Education (Education)
Re: If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

lipsi18 wrote:
A clock can be divided in 12 equal parts, to find out the shaded region more than 10 minutes or not, we need radios of the clock and angle made by the clock for that region.

A) Radius =10 , shaded region angle is not given so insufficient
B) Area if given but angle and radius is not known, so insufficient

Together A+B) we have radius and area of the sector, so we can find out the angle of the sector, so Sufficient

Hence answer is C
Thanks,

Please check the highlighted part and Statement 2.

Statement 2 clearly tells us that that The area of the sector is more than 16π.

which doesn't tell us exact area but it just provides us the range of Areas and in such cases it's NECESSARY to check if the Range gives us a consistent answer or NOT.

Unfortunately the range doesn't provide a consistent answer and hence it's not sufficient
_________________
Prosper!!!
GMATinsight
Bhoopendra Singh and Dr.Sushma Jha
e-mail: info@GMATinsight.com I Call us : +91-9999687183 / 9891333772
Online One-on-One Skype based classes and Classroom Coaching in South and West Delhi
http://www.GMATinsight.com/testimonials.html

ACCESS FREE GMAT TESTS HERE:22 ONLINE FREE (FULL LENGTH) GMAT CAT (PRACTICE TESTS) LINK COLLECTION
Math Expert V
Joined: 02 Sep 2009
Posts: 58453
Re: If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

Bunuel wrote: If O represents the center of a circular clock and the point of the clock hand is on the circumference of the circle, does the shaded sector of the clock represent more than 10 minutes?

(1) The clock hand has a length of 10.
(2) The area of the sector is more than $$16\pi$$.

Kudos for a correct solution.

Attachment:
2015-06-24_1004.png

MANHATTAN GMAT OFFICIAL SOLUTION:

First of all, note that this is a Yes/No Data Sufficiency question.

The question “Does the shaded sector of the clock represent more than 10 minutes?” is really asking you about the area of a sector of a circle.

Since 10 minutes is 1/6 of an hour, you are being asked if the shaded region is equal to more than 1/6 of the area of the circle.

(1) INSUFFICIENT: The “clock hand” is equal to the radius. Knowing that the radius = 10 is enough to tell you that the entire area of the circle is equal to 100#. You can rephrase the question as, “Is the area of the shaded region more than one-sixth of $$100\pi$$?” You can simplify 1/6 of 100# as such:

$$\frac{100\pi}{6}=16.(6)\pi$$

Thus, the question can be rephrased as, “Is the area of the shaded region more than $$16.(6)\pi$$?” However, you don’t know anything about the area of the shaded region from this statement alone.

(2) INSUFFICIENT: The area of the sector is more than $$16.(6)\pi$$. By itself, this does not tell you anything about whether the area of the sector is more than 1/6 the area of the circle, since you do not know the area of the entire circle.

(1) AND (2) INSUFFICIENT: The area of the entire circle is $$100\pi$$, and the area of the sector is “more than $$16.(6)\pi$$.” Since 1/6 of the area of the circle is actually 16.6#, knowing that the area of the sector is “more than 16#” is still insufficient — the area of the sector could be $$16.1\pi$$ or something much larger.

The correct answer is E.
_________________
Non-Human User Joined: 09 Sep 2013
Posts: 13264
Re: If O represents the center of a circular clock and the point of the cl  [#permalink]

Show Tags

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________ Re: If O represents the center of a circular clock and the point of the cl   [#permalink] 24 Mar 2018, 05:52
Display posts from previous: Sort by

If O represents the center of a circular clock and the point of the cl

 new topic post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne  