Work/Rate problem

[BTGmoderatorRO]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000
OA is c.
Can any expert help me with the best approach to use here? Thank you

[GMATGuruNY]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000

Use the following equation:

(machines)(time) / output = (machines)(time) / output

In the equation above:
Machines and time are INVERSELY PROPORTIONAL.
As the number of machines increases, the amount of time required to produce the same output decreases.
Machines and output are DIRECTLY PROPORTIONAL.
As the number of machines increases, the amount of output also increases.
Time and output are also DIRECTLY PROPORTIONAL.
As the amount of time increases, the amount of output also increases.

In the problem above:
(4 machines)(1 minutes)/(220 candles) = (10 machines)(5 minutes)/(x candles)
4x = 220*10*5
x = 55*10*5 = 2750.

The correct answer is C.

[Brent@GMATPrepNow]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000

Given: 4 machines produce 220 candles per ONE minute
So, 1 machine produces 55 candles per ONE minute
Therefore, 10 machines produce 550 candles per ONE minute
And 10 machines produce 2750 candles per FIVE minute

Answer: C

Cheers.
Brent

[Jeff@TargetTestPrep]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000

We can determine the rate of 10 machines with the following proportion:

4/220 = 10/x

4x = 2200

x = 550

We know that 10 machines can produce 550 candles in one minute. Thus, in 5 minutes, 10 machines can produce 550 x 5 = 2750 candles.

Answer: C

[[email protected]]

Hi Roland2rule,

We're told that 4 identical machines (working at the same rate) can produce a total of 220 candles per minute. We're asked for the number of candles that 10 such machines could produce in 5 minutes. There are a number of different ways to approach this type of math (depending on how comfortable you are with the arithmetic involved). Since the answer choices are so 'spread out', you can also use them to avoid some of the math involved.

The initial data discusses 4 machines working for 1 minute each.
The question discusses 10 machines working for 5 minutes each.

Clearly, we have 2.5 times the number of machines and they're each working for 5 times more time. (2.5)(5) = 12.5.... so we're looking for an answer that is 12.5 times 220....
12.5 is greater than 10... so if we're going to estimate, then we need an answer that's a bit greater than (10)(220)...So which answer is a bit more than 2200? There's only one answer that matches...

Final Answer: C

GMAT assassins aren't born, they're made,
Rich

[Brent@GMATPrepNow]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000

Given: 4 machines produce 220 candles per ONE minute
So, 1 machine produces 55 candles per ONE minute
Therefore, 10 machines produce 550 candles per ONE minute
And 10 machines produce 2750 candles per FIVE minute

Answer: C

Cheers.
Brent

[Brent@GMATPrepNow]

Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000
OA is c.
Can any expert help me with the best approach to use here? Thank you

[benjemin28]

Hello, Brent@GMATPrepNow,

Roland2rule wrote:
Operating at the same constant rate, 4 identical machines can produce a total of 220 candles per minute. At this rate, how many candles could 10 such machines produce in 5 minutes?
(A) 512
(B) 2,200
(C) 2,750
(D) 11,000
(E) 44,000
Given: 4 machines produce 220 candles per ONE minute
So, 1 machine produces 55 candles per ONE minute
Therefore, 10 machines produce 550 candles per ONE minute
And 10 machines produce 2750 candles per FIVE minute

Answer: C

Your right answer to suggest to me but I don't know which method to use & solve the question can you please suggest me which process to use suggest the method.
Thanks!

[[email protected]]

Hi benjemin28,

It's worth noting that he Quant section of the GMAT is NOT a 'math test' - it's a 'critical thinking test' that requires lots of little calculations as you work through it. Most GMAT questions are designed so that they can be solved in more than one way (and certain Tactics can help you to answer questions faster than doing 'traditional math'). Thus, if your Goal is to score at a really high level on the GMAT, beyond learning the content, you also will have to learn the patterns, Tactics and little 'secrets' to the Exam.

If you read through the posts in this thread, you will see a number of different ways to approach this question - and they all lead to the correct answer. Which ways are you comfortable with? Which method would be fastest?

GMAT assassins aren't born, they're made,
Rich