(0.513)(0.488)(0.942)/(0.684)(0.314)(0.183)

Question

What is the fastest way to solve this?

\frac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)}

a) 4
b) 5
c) 6
d) 7
e) 8

u1983 · Accepted Answer

I would like to use approximation of numbers as below:

\frac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)} 
 = \frac{(513)(488)(942)}{(684)(314)(183)} 
apx= \frac{(500)(500)(950)}{(700)(300)(190)} 
apx= \frac{(5)(5)(5)}{(7)(3)} 
apx= \frac{(5)(5)(5)}{(7)(3)} 
apx= \frac{(125)}{(21)} 
apx=6....................(21*6=126)................................Thus  Answer c

Tulkin987 · Answer

\frac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)}   =   \frac{(3*0,171)(8*0,061)(3*0,314)}{(4*0,171)(0.314)(3*0,061)}   =  6

Answer: C

push12345 · Answer

Take approximate values and solve

0.5*0.5*1/(0.7*0.3*0.2)
=125/21
Approx 6
as 21*6=216

Posted from my mobile device

dabaobao · Answer

1) Remove all the decimals
2) 942/314 = 3
3) If you can't see other obvious big factors, then just try to use smaller factors to reduce.
4) You'll get reduced fraction as 6.

ANSWER: C

Crytiocanalyst · Answer

The fraction has to be simplified
=>(3*0.171*8*0.061*3*0.314)/4*0.171*0.314*3*0.061

=>3*8*3/4*1*3
=>6 
Therefore IMO C

Rail · Answer

you can also try to do the following

(1/2*1/2*1)/(7/10*3/10*2/10)

leading to approx (1/4)/(42/1000) (do not reduce denominator before last passage)

then 1/4*1000/42 which leads up to 250/42 that is approx 6

bottom line: i'd try to get rid of decimals as soon as possible, therefore managing to get to the correct answer in under 2 min. you can approximate here since the answers are pretty spread apart

hope it is useful

BrentGMATPrepNow · Answer

Useful concept:  \frac{A 	imes B 	imes C}{D 	imes E 	imes F} = \frac{A}{D} 	imes \frac{B}{E} 	imes \frac{C}{F}

Strategy: As you can imagine, we certainly don't want to actually find the product in the numerator and the product in the denominator and then divide the results. Instead, let's invest a little bit of time identifying any pairs of values that might simplify today " nice" fraction.

First off, I recognize that  0.942  is exactly  3 	imes 0.314 .

So, let's rewrite our expression as follows:  \frac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)} = \frac{0.942}{0.314} 	imes \frac{(0.513)(0.488)}{(0.684)(0.183)}= 3 	imes \frac{(0.513)(0.488)}{(0.684)(0.183)}

Next, I know that  3 	imes 0.18 = 0.54 , which means  \frac{0.54}{0.18} = 3

The fraction  \frac{0.513}{0.183}  kind of resembles  \frac{0.54}{0.18} = 3 . 
However, since  0.513  is a bit smaller than  0.54 , and since  0.183  is a teeny bit bigger than  0.18 , we know that  \frac{0.513}{0.183}  will be a little bit smaller than  3 .

So, we can rewrite our expression as follows:  3 	imes \frac{(0.513)(0.488)}{(0.684)(0.183)} = 3 	imes \frac{0.513}{0.183} 	imes \frac{0.488}{0.684} = 3 	imes little less than3 	imes \frac{0.488}{0.684}

Finally, we know that  \frac{4}{6} = \frac{2}{3} , and  \frac{440}{660} = \frac{2}{3} , and  \frac{460}{690} = \frac{2}{3}

Since  0.488  is a bit bigger than  460 , we can conclude that  \frac{0.488}{0.684}  is a little bit bigger than  \frac{2}{3} .

So, our expression becomes:
 3 	imes little less than3 	imes \frac{0.488}{0.684} = 3 	imes (little less than3) 	imes (a little more than \frac{2}{3})

The "little more than part" some What cancels out with the " little less than" part to get:  3 	imes 3 	imes \frac{2}{3} , which evaluates to be  6

Answer: C

udaypratapsingh99 · Answer

Factorise it 
 
( 3* 0.171) ( 8* 0.61) ( 3* 0.314) 
( 4* 0.171) (0.314) ( 3* 0.61)

=6

C is the correct answer.

Pulkit2605 · Answer

0.942/0.314 = 3
therefore
0.5*0.5*3 divided by 0.7*0.2
25*3 divided by 14
75 divided by 14
approx = 5

Y the answer is coming wrong when we approach in this manner ?

Crater · Answer

\frac{(0.513)(0.488)(0.942)}{(0.684)(0.314)(0.183)}

Remove decimals

\frac{(513)(488)(942)}{(684)(314)(183)}

942/314=3 was pretty straightforward

\frac{(513)(488)(3)}{(684)(1)(183)}

This is the trickiest part, but I prime factorised odd numbers first to look for patterns:

\frac{(3*171)(8*61)(3)}{(4*171)(1)(3*61)}=~6

Hence the answer is six.

Nightscrapper52 · Answer

I got the logic why answer is 6, but there are chances to end up at 5. How can such mistakes be avoided?  Bunuel

Posted from my mobile device

walterwhite756 · Answer

I get your question, based on some far fetched assumptions, one can arrive at answer 5 too. For that, you need to balance what values you're approximating. Suppose if we're talking about a*b then if you assumed a's value larger than a then keep in mind that you need to be assume B's value slightly lower in order to arrive at correct a*b. Inverse applies when we talk about a/b.

However, keep in mind that GMAT will rarely ask such question in which answer choices will be so close as to cause these mistakes. Have a clear approach in mind, and you'll reach at right answer. Also fractionals values may be remembered, which will help in long way for such questions.

Crater · Answer

In this case since the answer values are close, it comes down to degree of approximation. My strategy is reducing the numbers till I can find a pattern (GMAT usually have a pattern for harder questions) and approximate close to the answer. (It is time consuming though)!

kokus · Answer

1/2*1/2*19/20 / 2/3*1/3*3/16 -> 19/80 / 1/24 -> 1/4*24/1 -> 24/4 -> 6

Aboyhasnoname · Answer

Somebody Please Help me, I used the approximations.....

I approximated to the nearest tenth digit.......and made it (0.5 X 0.5 X 0.9)/ (0.7 X 0.3 X 0.2 )..This gives me.....around 5. something.... 
Now How am I supposed to know if the answer will be 5 or 6?

Ngocanhvy · Answer

it's clever but i am not sure i gonna be able to deduce anything like 0.513 - 9.172 *3 t.t espcially under the time constraint and test anxeity

(0.513)(0.488)(0.942)/(0.684)(0.314)(0.183)

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

(0.513)(0.488)(0.942)/(0.684)(0.314)(0.183)

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards