Question

easy question will give medal

Answer 1

@Indivicivet

Answer 2

The fourth option, surely?

Answer 3

\[M' = U \backslash M = U - M\]
M' is the numbers in U that aren't in M.

Answer 4

@radar @RaphaelFilgueiras @dirtydan667

Answer 5

17. You want to save x a week for 4 weeks. After 4 weeks you will have 4x. 4x must be greater than or equal to 240.

18.
\[\frac{98+87+x_\text{low}}{3} = 90\]
\[\frac{98+87+x_\text{high}}{3} = 95\]
\[x_\text{low} \leq x \leq x_\text{high}\]

19. The people who only like comedies can't be the same people as the people who only like thrillers or the people who only like both. 256-116-78

Answer 6

is 17. B
18. B
19. A

Answer 7

19 is right but the other two are not.

For 17, you know four times x has to be at least 240
\[4x \geq 240\]

divide both sides by 4:

\[x \geq 60\]

If you check your answers to 18 you get:

\[\frac{98+87+90}{3} = 91.\dot{6} \neq 90\]

\[\frac{98+87+95}{3} = 93.\dot{3} \neq 95\]

You could try rearranging
\[\frac{98+87+x_\text{low}}{3} = 90\]
Multiply both sides by 3:
\[98+87+x_\text{low} = 270\]
subtract (98+87) from both sides to get the lower limit.

Then try almost the same thing for the upper limit?

Answer 8

17. A
18. ?

Answer 9

@broken_symmetry im confused

Answer 10

It's ok.

Which part is confusing?

Answer 11

im not sure how to figure out the answer to 18
is 17 right

Answer 12

17 is right, yes.

Which part of 18 are you stuck with?

Answer 13

wait would the answer be A for 18

Answer 14

@broken_symmetry

Answer 15

No :(

Ok, let's walk through this. The student has a 98 and an 87 already. The average of this would be
\[\text{Average} = \frac{\text{Sum of scores}}{\text{Number of tests}} = \frac{98+87}{2} = 92.5\]

There's a third test coming up, and once the student has finished it, the average will then be:

\[\text{Average} = \frac{\text{Sum of scores}}{\text{Number of tests}} = \frac{98+87+\text{third test score}}{3}\]

The question tells us that we want to find the two possible scores the student can get on the third test in order to get an average of either 90 or 95. This means

\[\frac{98+87+\text{lower score}}{3} = 90\]
and

\[\frac{98+87+\text{higher score}}{3} = 95\]

Now can you work out what the lower score and the higher score should be?

Answer 16

85 and 100?

Answer 17

That's right :D

Answer 18

yes
thanks