Simple Maths Problem

[dr_gn]

Toltec said:

dr_gn said:

Worded incorrectly for the answer they gave, NOT ambiguously. Their answer was stated on page 1 of this thread BTW.

I can draw a diagram to explain it if you like, but it’s really not difficult to understand once you get beyond what you automatically tend to calculate vs. what they actually ask.

Just asked the question of two very smart people, 50/50 split on the answer, however the 7/48 was partially because he took it that the question must be non-trivial as I had asked it so chose the less obvious answer. Which is the point you are making clearly.

Interestingly if you want to pick hairs the idea that two cakes could actually be identical was questioned, however we reached the hypothesis that the cakes had been produced from a master cake using a quantum level duplication device of some kind and the slices cut almost instantaneously thereafter.

I guess it comes down to assessing how likely it was the setter made a mistake or not, if you do not know the person or have not encountered previous tests set by this person, or at a lower utility similar tests by other people, then it becomes harder to assign a probability to this. I decided that the balance of probability was the question was poorly worded and therefore chose the answer that the setter obviously expected to receive.

Deliberately putting the wrong answer is a risky strategy in an exam. At the risk of ridicule, here’s how I visualised the problem:



It’s as much about wording as maths, but I really can’t see how anyone could assume the answer related to a single cake - the wording is not even ambiguous - it’s definitely plural, not singular.

The only way the answer could be 7/24 was if it explicitly said “...a cake...”

Or am I missing something more subtle in the wording or maths?

[dr_gn]

Einion Yrth said:

After consideration, it is clear that the "correct" answer is 7/48. It is also clear that the setter merely wished to test the students' ability to find the lowest common denominator and perform a subtraction between fractions.
Conclusion; the setter's an idiot.

Yup. Plus it’s a revision book for SATS, so the last thing a 9 year old needs is to be confused/frustrated when they’re already feeling a bit of pressure, and trying to learn.

[dr_gn]

anonymous said:

[redacted]

You didn’t define the question though:

It’s entirely correct if you ask the question “how much cake is left in terms of the percentage of a whole cake?”

It’s entirely incorrect if you simply ask “how much cake is left?”

[dr_gn]

anonymous said:

[redacted]

I am the OP!

Just saying that it depends entirely on wording. It never occurred to me that the answer to the original question could be anything other than 7/48.

[dr_gn]

Some Gump said:

I find it amazing that anyone can have a grasp of maths this bad, especially the f1 stats guru.

Only got though page 1, but throughout I was subconsciously adopting that sad downward headshake teachers use a lot!

Out of interest, what answer do you think it is?