Hi,
This is how I arrived at the answers:-
Let the sales for the period 1990-95 be 'x'
Therefore, the sales for the period 1995-2000 is '1.52x'
Now, total sales for the period is 'x+1.52x=2.52x=3843'
Solving we get x=1525.
Since the question asks for the closest approximation we can approximate the value of x to 1530.
Therefore, sales for the period 1990-95 is 1530 (after closest approximation)
and, sales for the period 1995-2000 is 2318.
Hence, the sales for the period 2000-05 is 2x2318=4636 which after approximation would be 4640.
hope it helps.
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I think this way 2000-2005 years /1990-1995 years =1.52*2=3.04
if we divide 4640 to 1530 we get that approx. 3.04
right?

do you have any other thoughts how to solve it?
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No worries guys, you'll have access to the on-screen calculator for the Integrated Reasoning section of the exam. At times, you may want to use the calculator to do some real-world calculations quickly. Weird decimals or percentages are fair game on the IR section.

Hi All,

This prompt is more about organization and basic arithmetic than anything else. You do NOT need the calculator as long as you take good notes, make some reasonable estimates and do some multiplication.

From the information in the prompt, we can make a little table of data (based around three 5-year 'blocks' of time):

'90-'95: 2500 books published; X books sold
'95-'00: >2500 published; 1.52X books sold

Total books sold '90-'00 = 3843 = 2.52X

From here, you should quickly note that X MUST be > 1,000. A reasonable estimate would be X = 1500 (try multiplying 2.5 by 1500 and you'll see).

'00-'05: 2(1.52X) books sold = 3.04X books sold

The question asks for TOTAL BOOKS SOLD from '90 - '95 and from '00-'05

Using X = 1500 as an estimate....
'90-'95 = X = 1500 books sold

'00-'05 = 3.04X = about 4500 books sold

From the given values in the table, the only answers that are close are:

GMAT assassins aren't born, they're made,
Rich
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in period 190-1995 , the number sold is x
in 1995-2000, the number is 1.5 x

x+1.5x= 3.8
x=1.5
1.5x=2.3

the periond 2000-2005 is doble of 2.3 so, it is 4.6

the correct is

1.5 and 4.6

There is no use to do tedious calculations, The GMAT way is to approximations.

let the sale done in 1990-95 period be x

Since the sales for period 1995-2000 increased by 52% over the previous 5 year period, then we can approximate it as 50% increase.

Therefore, x+1.5x= 4000 ( approximating 3843 to 4000)

2.5x= 4000

x= 4000/2.5 = 1600

The number closest to 1600 is 1530, so that's the correct answer.

Also 1.5x = 2400( from above)

Sales for 2005-05 period is doubled over previous period

Therefore sales for 2000-05 period = 2 * 2400 = 4800

4640 is the option closest to 4800, hence that is the correct ans.

You can easily do all this calculations in your head in matter of 2 minutes but only if you approximate.

Dear,
Thanks for the explanation. I was just lost before I read this post. But the information "that 2500 copies were published in 1990" is useless for this problem?

Thanks!
Regards
Andy

Yes, you have not been given any information from this statement how many of those 2500 books were actually sold. But in the next line it is mentioned that 50% more books were sold from 95-2000 and that the total till 2000 was 3843 books.

So, you can setup the equations like this:

Let books sold in 90-95 = x ---> books sold from 95-2000 = 1.52x (as it is 52% more)

Thus x+1.52x = 3843 ----> x=1525 books.

Also given is that during the period 2000-2005, twice the number of books sold in the period 95-2000 were sold. Thus books sold in 2000-05 period = 2*1.52x = 3x = 4636 books.

Thus you have the 2 answers.
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