QUESTION TEXT: Auditor: XYZ, a construction company, purchased 20…
QUESTION TYPE: Necessary Assumption
CONCLUSION: None of the trucks purchased 3 years ago were diesel powered.
REASONING: The company purchased 20 trucks 3 years ago. They sold none of those trucks this year, but they did sell all of their diesel trucks this year.
ANALYSIS: I found this question very difficult, and had to read it three times then come back to it. If the company sold all its diesel trucks last year, how could it not have sold any of the 20 trucks 3-year old if they were diesel powered?
It turns out I made a simple oversight. What if the company sold some of the 20 trucks last year, or two years ago?
I’ll give a numerical example. Let’s say the company owned five diesel trucks of type X. Three years ago, they bought four diesel trucks of type D. They also own two regular trucks, type T.
Two years ago, they sell all D trucks. And last year year they sell all their remaining diesel trucks, the X’s. Here’s the stock of trucks at the end of each year:
Four years ago: XXXXX TT
Three years ago: XXXXX DDD TT
Two years ago: XXXXX DDD TT
Last year: XXXXX TT
This year: TT
So in this example, the company did buy diesel trucks three years ago (DDD). It didn’t sell them last year, but only because it already sold them two years ago.
- Not required.
Negation: One truck sold last year was gasoline powered, the rest were diesel.
- Who cares what used trucks the company bought? The stimulus is about the 20 new trucks.
Negation: The company also bought a used truck 3 years ago.
- It doesn’t matter whether the company bought other trucks. We only care about the 20 trucks bought three years ago.
Negation: Two years ago, the company bought a new gasoline powered truck.
- CORRECT. If some trucks were sold two years ago, then they could have been diesel trucks even though they weren’t sold last year.
Negation: The company sold some of the 20 trucks earlier than last year.
- We don’t care about trucks purchased more than 3 years ago. The question is about trucks purchased exactly 3 years ago.
Negation: The company still has a truck it bought 18 years ago. Wowza!
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