Question

Brad and Tom are comparing their classes' scores on a math test. Both of their classes had mean scores of 80 on the test, but Brad's class had a range of 6 while Tom's class had a range of 30. If the highest possible score was 100, which class had the LOWEST score in it?
A)
Brad's class had the lowest score in it.
B)
Tom's class had the lowest score in it.
C)
The lowest score occurred in both classes.
D)
It cannot be determined from the information.

Answer 1

sd is approx = r/4 not that it helps

Answer 2

ok lol thanks anyways :)

Answer 3

it doesnt mention that its a normal distribution; it doesnt mention the size of each class .... youd be prone to thing that the range of 30 has the lowest grade tho

Answer 4

the mean doesnt even imply that anyone got an 80 at all

Answer 5

The answer is Tom's class. Here's why:

If the highest possible score is 100, and the range in Tom's class is 30, then the lowest score was *at most* 70 (100-30). However, the lowest possible score in Brad's class is at least 74 (80-6). This is because:
1) Every score in Brad's class can't be below the mean
2) Therefore there must be at least one score in Brad's class that is greater than or equal to 80 (the mean).
3) Because the range is 6, the lowest possible score in Brad's class is *at least* 74 (80-6).

So we know that
(The lowest score in Brad's class) >= 74 > 70 >= (The lowest score in Tom's class),

and so Tom's class must have had the lowest score.

Answer 6

does highest possible mean that it was obtained?

Answer 7

at most and at least .... still have to read those lol

Answer 8

No, but it doesn't matter :-). The point is that the lowest score, whatever it actually was, could not have been above 70. If you know it's below 70, even if you don't know the actual value, that's enough to finish the problem.

Answer 9

ill trust your judgement on that, but i still hold my reservations ;)