It is currently 20 Oct 2017, 20:19

### 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

# Help with Quant Q (greater explanation)

Author Message
Intern
Joined: 09 Jan 2009
Posts: 10

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

Schools: harvard
Help with Quant Q (greater explanation) [#permalink]

### Show Tags

29 Jan 2009, 11:42
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Can someone help explain in greater detail Step 2 and 3 in the below?

(1/5)^m*(1/4)^18 = 1/2(10)^35
Step 1) (1/5)^m*(1/2)^36 = 1/2(10)^35 {since 2^2=4}
Step 2)(1/5)^m*(1/2)^m*(1/2)^(36-m) = 1/2*1/(10)^35
Step 3)(1/10)^m*(1/2)^(36-m) = 1/2*(1/10)^35
equate indices from both sides. i.e. equate index of (1/2) and (1/10).
left hand side =1/2*(1/5^35)*(1/2)^35 hence, m=35

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

GMAT Tutor
Joined: 24 Jun 2008
Posts: 1339

Kudos [?]: 1954 [0], given: 6

Re: Help with Quant Q (greater explanation) [#permalink]

### Show Tags

29 Jan 2009, 12:48
jaycurtis wrote:
Can someone help explain in greater detail Step 2 and 3 in the below?

(1/5)^m*(1/4)^18 = 1/2(10)^35
Step 1) (1/5)^m*(1/2)^36 = 1/2(10)^35 {since 2^2=4}
Step 2)(1/5)^m*(1/2)^m*(1/2)^(36-m) = 1/2*1/(10)^35
Step 3)(1/10)^m*(1/2)^(36-m) = 1/2*(1/10)^35
equate indices from both sides. i.e. equate index of (1/2) and (1/10).
left hand side =1/2*(1/5^35)*(1/2)^35 hence, m=35

That's an unconventional solution - nothing wrong with it, but I'm not sure many people would think to introduce the fraction(1/2)^m at step 2, especially since there isn't any reason to. You can do as follows, which I'd personally find simpler, using prime factorizations to ensure we have the same base numbers:

$$\left(\frac{1}{5} \right)^m \times \left( \frac{1}{4} \right)^{18} = \frac{1}{2 \times 10^{35}$$

$$\left(\frac{1}{5^m} \right) \times \left( \frac{1}{(2^2)^{18}} \right) = \frac{1}{2 \times (2 \times 5)^{35}$$

$$\frac{1}{5^m \times 2^{36} } = \frac{1}{2 \times 2^{35} \times 5^{35}$$

$$\frac{1}{5^m \times 2^{36} } = \frac{1}{2^{36} \times 5^{35}$$

$$m = 35$$
_________________

GMAT Tutor in Toronto

If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com

Kudos [?]: 1954 [0], given: 6

Manager
Joined: 13 Jan 2009
Posts: 170

Kudos [?]: 26 [0], given: 9

Re: Help with Quant Q (greater explanation) [#permalink]

### Show Tags

30 Jan 2009, 04:24
Everything is clear!

Kudos [?]: 26 [0], given: 9

Intern
Joined: 09 Jan 2009
Posts: 10

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

Schools: harvard
Re: Help with Quant Q (greater explanation) [#permalink]

### Show Tags

30 Jan 2009, 09:30
Thanks that makes much more sense!!!

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

Re: Help with Quant Q (greater explanation)   [#permalink] 30 Jan 2009, 09:30
Display posts from previous: Sort by