Standard Math Q+A Thread

[RuiAce]

Just wondering If anyone can help me solve this multiple choice question ? thank you
21 Which equation correctly shows r as the subject of S = 800(1 – r)?
(A) r = 800 – S
             800
(B) r = S – 800
             800
(C) r = 800 – S
(D) r = S – 800

[aimbotted]

how's everyone feeling for tommorow?

[pughg16]

how's everyone feeling for tommorow?

scared.

Can I have some help in this question please?

Ali's class sits 2 geography tests. The results of her class on the first test are:
                          58, 74, 65, 66, 73, 71, 72, 74, 62, 70
The mean was 68.5 for the first test, and calculated Standard deviation was 5.2
For the second test, the mean was 74.4 and the standard deviation was 12.4
Ali scored 62 on the first test. Calculate the mark that she needed to obtain in the second test to ensure that her performance relative to the class was maintained.

[Gregs]

Hi Rui for this question if it wasn't a multiple choice question I'd probably do

S= 800-800r

S-800 = -800r

(S-800)/-800 = r

Why wouldn't that be right?

[RuiAce]

Hi Rui for this question if it wasn't a multiple choice question I'd probably do

S= 800-800r

S-800 = -800r

(S-800)/-800 = r

Why wouldn't that be right?

But whether or not you'd be marked wrong is not something for me to comment on.

[mfaith99]

how's everyone feeling for tommorow?

I don't know why, but I'm not feeling very stressed, usually I would be, but for this exam I feel properly prepared for once!

[Gregs]

scared.

Can I have some help in this question please?

Ali's class sits 2 geography tests. The results of her class on the first test are:
                          58, 74, 65, 66, 73, 71, 72, 74, 62, 70
The mean was 68.5 for the first test, and calculated Standard deviation was 5.2
For the second test, the mean was 74.4 and the standard deviation was 12.4
Ali scored 62 on the first test. Calculate the mark that she needed to obtain in the second test to ensure that her performance relative to the class was maintained.

So for this it's pretty much asking how far away from the mean she is in regards to the z-scores
-1 z-score = 63.3
-2 z-scores = 58.1
so Ali is somewhere in-between these two scores to work how far off of a z-score she is minus the 63.3 by her score
= 1.3 marks
1.3 marks is 1 quarter of a standard deviation ( 1.3/5.2 = 0.25)
so that means her mark is 1.25 standard deviations away from the mean
This means to stay relative to her class Ali needs to score a mark that is -1.25 standard deviations of the mean of the second test
1.25 x 12.4 =15.5
74.4-15.5 = 58.9
Ali needs to score a mark of 58.9 for her performance to stay relative to the class

 

[Gregs]

But whether or not you'd be marked wrong is not something for me to comment on.

Oh right I left a step out, Cheers Rui

[RuiAce]

I don't know why, but I'm not feeling very stressed, usually I would be, but for this exam I feel properly prepared for once!

Good on you. It means you'll kill it tomorrow

[pughg16]

So for this it's pretty much asking how far away from the mean she is in regards to the z-scores
-1 z-score = 63.3
-2 z-scores = 58.1
so Ali is somewhere in-between these two scores to work how far off of a z-score she is minus the 63.3 by her score
= 1.3 marks
1.3 marks is 1 quarter of a standard deviation ( 1.3/5.2 = 0.25)
so that means her mark is 1.25 standard deviations away from the mean
This means to stay relative to her class Ali needs to score a mark that is -1.25 standard deviations of the mean of the second test
1.25 x 12.4 =15.5
74.4-15.5 = 58.9
Ali needs to score a mark of 58.9 for her performance to stay relative to the class

Thankyou!

[aimbotted]

Good on you. It means you'll kill it tomorrow

hahah thats how i always feel before every test, until i actually get in the room and realize how fucked i really am

[RuiAce]

hahah thats how i always feel before every test, until i actually get in the room and realize how fucked i really am

Oh nah that was me last year. And then I got high marks anyway.

So long as your good feelings are justified then it usually comes out well. If you feel good on no study then, well...

[Sssssrr]

could someone please help me with this question?
thanks in advance

[aimbotted]

maximum value of absolute error = 1/2 = 0.5

0.5/49 x 100 = 1.02% so 1%

[pughg16]

Could someone please help me with this question?
I can never get how to read these tables, or what they actually mean.