Eageleeye & niket,
First of all i had to admit this is a tough cookie....750+ level question. But anyway here is the explanation
OA is B
The prompt describes an annual report that includes a pie chart in which each sector represents the percentage of total minerals sales generated by a certain mineral. The size, and thus the central angle, of each sector is proportional to that percentage.
We are told that last year, the central angle of the sector representing cobalt sales was larger than the central angle of the sector representing iron sales. In other words, cobalt sales represented a larger percentage of total mineral sales than did iron sales.
Moreover, we are told that the measure of the central angle of the sector representing cobalt sales is 50% greater this year than it was last year. Since the central angle increases by a factor of 1.5, cobalt sales this year represent 1.5 times the percentage of total mineral sales that they did last year.
We are asked whether cobalt sales generated more revenue this year than did iron sales. If we can determine whether the percentage of revenue from cobalt sales was greater than that from iron sales, or if we can determine whether the central angle of the sector representing cobalt was greater than that of the sector representing iron, we can answer the question.
Statement 1 alone tells us that the revenue from the sale of iron this year is 70% greater than the revenue from the sale of iron last year. Notice that this is an increase in absolute terms, not necessarily in terms of iron's share of total sales. We are interested in iron sales relative to the sales of other minerals (cobalt in particular), not absolute sales. The increase in iron sales could be a significant increase relative to the sale of other minerals. Or, it could be that sales of all minerals increased by at least 70%. In that case, the percentage of revenue from mineral sales generated by iron sales might actually have decreased. Since we cannot know which scenario is accurate, Statement 1 alone is not sufficient. Eliminate answer choices A and D.
Statement 2 alone tells us that last year, the combined sales of cobalt and iron generated more than 68% of the company's total revenue from minerals sales. Remember that cobalt sales last year made up a larger percentage of total sales than did iron sales. So cobalt sales last year must have been more than 68% ÷ 2 = 34% of the total revenue from minerals sales.
Since cobalt sales this year represent 1.5 times the percentage that they did last year, cobalt sales this year must be more than 1.5 × 34%-that is, more than 51%-of total sales. That means that even if iron were the only other mineral sold this year, iron sales must be less than 49%, since the total of the percentages of all minerals sales is 100%. Cobalt sales this year must have generated more revenue than iron sales. Statement 2 alone is sufficient.
Answer choice B is correct.
Regards,
Karthik
The source of the questions that i post from JUNE 2013 is from KNEWTON
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