Warehouse W's revenue from the sale of sofas was what percent greater this year than it was last year?

(1) Warehouse W sold 10% more sofas this year than it did last year
(2) Warehouse W's selling price per sofa was $30 greater this year than it was last year

That is the OA, nice job.

Had we been provided with the % price increase rather than $ amount, would C be the answer or still E?

Def E.

1: (1.1x-x)/(x) Insuff we dont know what the REVENUE was.
2: insuff nothing about the amount of sofas.

Together best we can get is (1.1(x+30) - (x))/x

Hello,

Let me try helping you.

Warehouse W's revenue from the sale of sofas was what percent greater this year than it was last year?

1) Warehouse W sold 10% more sofas this year than it did last year
2) Warehouse W's selling price per sofa was $30 greater this year than it was last year

We need to find the percentage increase in the revenue of Warehouse X. This would normally be calculated as (X-Y)/X where would be the revenue this year and y would be the revenue last year.
Remember, Total revenue= Number of sofas sold * cost of sofas

Let us analyze the options now
1) This tells is about the percentage increase in sale of sofas. However, even though we know about the percentage increase in the number of sofas sold, we do not know anything about the selling price of these sofas in either years and hence, information is insufficient.

Statement 2) also gives us information about the difference in selling price per sofa in both years. However, we do not know the number of sofas sold. INSUFFICIENT.

Together,
we know that the price of the sofa increase by $30 this year. We also know something about the percentage increase in the number of sofas sold.
Let us consider the number of sofas sold to be x last year. The number of sofas sold this year would be 1.1x. Now, let us consider the price of sofa last year to be y. The current price of the sofa would be y+30.
Percentage change would involve two different variables as shown below

(1.1x(y+30)-xy)/xy
All terms might cancel out but we will be left with a 30/y and since, we do not know the value of these variable, it would not be possible to calculate the percentage change. INSUFFICIENT
Answer is E.
Method 2)

Another way to solve this problem is to imagine, the increase in price.
Statement 1) would turn out to be insufficient because of the reason statement above.
Statement 2) gives us the increase in the price of the sofa. However, the 30 increase might be a huge increase if the beginning price of the sofa was $40. However, if the beginning price of the sofa was $300, then the percentage change would be very small.

Together, by reasoning similar to 2), the percentage change in the revenue might be very big or very small depending on the last year price of sofas. Hence, INSUFFICIENT.

This question could have been solved if the statements had given us either percentages in both statements or exact values in both statements.

Hope this helps! Let me know if I can help you any further.


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Kris
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Yes, in such a case the statements together would have been sufficient.
Let us try analyzing the situation you mentioned.

statement 1) is still insufficient since we do now know anything about the total revenue. Foe example, the change in selling price of the sofas could be 100% or even as small as 10%. Depending on the percentage increase in selling price, the percentage change in revenue would have to be calculated.
Statement 2) is still insufficient since all we know about is the percentage change in selling price. However, we still do not know much about the percentage increase in the number of sofas sold. For example, if the number of sofas sold increased by 80%, the percentage change would be very high. On the other hand, if it was as low as 10%, the percentage change could be lower.
However, note that we need to find a particular value of percentage change in the revenue. This percentage change cannot be found using either data alone.

Taking the statements together, we know the exact percentage change in the number of sofas(x and 1.1x) sold and the percentage increase in selling price(y and 1.3y). Hence, the percentage increase can be calculated and would be of the form
(1.1x*1.30y-xy)/xy
We can calculate a specific value for this and hence these statements are sufficient together.

Hope this helps! Let me know if I can help you any further.

_________________

Thanks
Kris
Instructor at Aspire4GMAT

Visit us at http://www.aspire4gmat.com

Post your queries
Join our free GMAT course

New blog: How to get that 700+
New blog: Data Sufficiency Tricks


Press Kudos if this helps!