It is currently 28 Jun 2017, 22:53

### 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

# Are you ready for GMAT? then try this

Author Message
TAGS:

### Hide Tags

Manager
Joined: 27 Feb 2010
Posts: 105
Location: Denver

### Show Tags

24 Apr 2010, 16:32
6
KUDOS
This attached document has really nice questions for practice. If you think you are ready for GMAT, try this
Attachments

Manager
Joined: 26 Feb 2010
Posts: 79
Location: Argentina

### Show Tags

26 Apr 2010, 12:09
Nice
thanks for sharing
I will try to resolve them
Manager
Joined: 27 May 2008
Posts: 126

### Show Tags

27 Apr 2010, 23:23
Thanks
Intern
Joined: 26 Mar 2010
Posts: 5

### Show Tags

02 May 2010, 14:51
My God, I got stuck with the following seemingly simple problem:

"If 7 workers can build 7 cars in 7 days, then how many days would it take 5 workers to build 5 cars?"

I solved this as follows:

49 worker/days - 7 cars
x - 5 cars

x = 35 worker/days are necessary to build 5 cars.

then let's divide 35 worker/days by 5 workers to receive 7 days.

But my approach may seem overcomplicated, so I will be grateful if you share other approaches to solving this problem.
Thanks.
Manager
Joined: 16 Feb 2010
Posts: 225

### Show Tags

02 May 2010, 19:08
joluwarrior wrote:
Thanks

I am not sure if you are aware of the RTD method but Rate * Time = Distance

Workers R T D
7 7 7
=> rate for 7workers is 1car per day
=> rate for 1 worker is :
7workers - rate 1
1worker - rate x
x= (1*1)/7=1/7

Workers R T D
5 * 1/7 * X = 5
===> X=(5*7)/5 = 7days
Manager
Joined: 16 Feb 2010
Posts: 225

### Show Tags

02 May 2010, 19:29
3. If p and q are prime numbers, how many divisors does the product (p^3)(q^6) have?

A) 9
B) 12
C) 18
D) 28
E) 36

OA: D

help !
cannt think of a way to figure this out...should be combinatorics.......
Intern
Joined: 26 Mar 2010
Posts: 5

### Show Tags

03 May 2010, 00:16
Thanks intern.
Of course i know RTD formula, but somehow I did not know how to apply to in this particular problem.
thanks.
Intern
Joined: 26 Mar 2010
Posts: 5

### Show Tags

03 May 2010, 00:39
Regarding the above problem with prime numbers, I do not know the answer as well, but I would like to share my guess:

a prime number is a number which can be divided by 1 or itself only. So the prime number has only two possible divisors.

The number p3 can seen as a product of 3 prime numbers, while each prime number has only 2 divisiors (1 and itself), so the maximum possible number of divisiors for p3 is 3x2=6.

Similarly with the number q raised to 6th power. It consists of 6 prime numbers with each prime number having only 2 possible divisors, so the maximum number of divisiors for q6 = 6x2=12.

Finally, the product of p3 and q6 will be all those divisors together (meaning 6+12). So my answer is 18.
Please someone with more expertise confirm or correct my approach.
Intern
Joined: 23 Jan 2010
Posts: 25
Concentration: Technology, Marketing

### Show Tags

03 May 2010, 02:18
1
KUDOS
I think the answer should be 28 as :

1. +1 for '1' which is a a factor for every number.
2. As they are prime , then factors of p=3(p,p-2,p-3) and for q6 ( similarly) 6 factors , total=9
3. The combonation of pq , say p(1) and for q 6 values total combinations=6 , similarly for p2 and p3 also 6 , which is total of 18.

All combined =1+9+18=28.

Please let me know if this is not correct..
Intern
Joined: 26 Mar 2010
Posts: 5

### Show Tags

03 May 2010, 02:55
dairymilk,

Your approach seems rather reasonable, especially in that you use "1" only once.

However, I think that in the number 18 (the number of combinations of p and q) there must be some repetitive combinations, because the three "p" are the same numbers, and the three "q" are the same numbers, and the order does not matter here.

Once again, I appreciate your contribution, dairymilk, and agree that it might be correct, but it would be great to finally hear the officially correct answer.

Thanks.
Intern
Joined: 14 Feb 2010
Posts: 14

### Show Tags

03 May 2010, 05:05
I solved the question on prime numbers using a formula that I had learnt a couple of years back -->

if N - p^2 x q^3, where p and q are prime numbers, the total number of divisors = (p+1)(q+1).

I had learnt this formula for CAT exam, probably from Arun Sharma's book on Quant or IMS material....I will be checking the book today to reassure that I remember the formula correctly.....will post my findings
Manager
Joined: 26 Feb 2010
Posts: 79
Location: Argentina

### Show Tags

03 May 2010, 10:47
zisis wrote:
3. If p and q are prime numbers, how many divisors does the product (p^3)(q^6) have?

A) 9
B) 12
C) 18
D) 28
E) 36

OA: D

help !
cannt think of a way to figure this out...should be combinatorics.......

For me the easy way is:
3+1 = 4
and 6+1 = 7
4x7 = 28
just add 1 to the exponents (if they are prime numbers) and then multiply
I hope it help
Manager
Joined: 28 Apr 2010
Posts: 64
Schools: CBS

### Show Tags

03 May 2010, 10:47
Awesome! Thanks for sharing.
Manager
Joined: 26 Feb 2010
Posts: 79
Location: Argentina

### Show Tags

03 May 2010, 10:58
Actually p and q must be different prime numbers
because if p = q then you have a different result
Manager
Joined: 26 Feb 2010
Posts: 79
Location: Argentina

### Show Tags

03 May 2010, 10:59
krishna3891 wrote:
Awesome! Thanks for sharing.

the thanks are for whom?
Manager
Joined: 28 Apr 2010
Posts: 64
Schools: CBS

### Show Tags

03 May 2010, 11:07
netrix wrote:
krishna3891 wrote:
Awesome! Thanks for sharing.

the thanks are for whom?

for the pdf contributor.
Intern
Joined: 14 Feb 2010
Posts: 14

### Show Tags

03 May 2010, 13:05
1
KUDOS
joluwarrior wrote:
I solved the question on prime numbers using a formula that I had learnt a couple of years back -->

if N - p^2 x q^3, where p and q are prime numbers, the total number of divisors = (p+1)(q+1).

I had learnt this formula for CAT exam, probably from Arun Sharma's book on Quant or IMS material....I will be checking the book today to reassure that I remember the formula correctly.....will post my findings

will specify 2 rules here - 1 directed at above question and the other at a similar question involving primes and divisors. These might help for quickly answering such questions.

1. The number of divisors of a composite number:
If D = (a^p)(b^q)(c^r), where a, b and c are primes, then the number of divisors of D, represented by 'n' is given by
n = (p+1)(q+1)(r+1)

2. The sum of divisors of a composite number:
For the same expression above D, sum of divisors S, is given by
S = [{a^(p+1) - 1}{b^(q+1) - 1}{c^(r+1) - 1}]/[(a-1)(b-1)(c-1)]
Manager
Joined: 16 Feb 2010
Posts: 225

### Show Tags

03 May 2010, 13:38
kudos netrix & joluwarrior

i was aware of the formula but totally forgot to use it in this scenario

I am working on a pdf document for explanations for all of the questions so feel free to contribute the shortest way of solving each question of the pdf on this topic.
Manager
Joined: 26 Feb 2010
Posts: 79
Location: Argentina

### Show Tags

03 May 2010, 13:41
zisis wrote:
kudos netrix & joluwarrior

i was aware of the formula but totally forgot to use it in this scenario

I am working on a pdf document for explanations for all of the questions so feel free to contribute the shortest way of solving each question of the pdf on this topic.

Hi zisis, thanks!
great work there
There are always different approach to a problem and we can learn them from the contribution of others
Intern
Joined: 26 Mar 2010
Posts: 5

### Show Tags

03 May 2010, 13:47

Thanks. I'm much more enlightened now
Re: Are you ready for GMAT? then try this   [#permalink] 03 May 2010, 13:47

Go to page    1   2    Next  [ 31 posts ]

Similar topics Replies Last post
Similar
Topics:
when do you try non-integer values? 2 26 Jun 2017, 12:26
1 GmatClub tests :Trying to improve quant score 2 12 Dec 2016, 21:32
5 Everything you need to know about ‘0’ for GMAT 0 04 Oct 2016, 22:13
4 Why You Should Convert Fractions to Decimals on the GMAT 0 17 Dec 2014, 07:03
41 Biggest GMAT Mistakes You Should Avoid 6 12 Jun 2016, 21:11
Display posts from previous: Sort by