Revision Qs help

[MicroShift]

Q12: Given r²=0.851, r=?
a) -0.922
b) 0.724
c) -0.724
d) 0.922
e) -0.426
Couldn't it be either a or d? Note that I don't have a graph for this data, so can't work out whether it's +/- based on that.
Q13: Given r=0.87, Mean of x=5.5, s_x=3.0, Mean of y=15.6, s_y=5.2 (x - independent variable, y - dependent variable). The gradient, b, of the least squares regression line y = a + bx, is closest to:
a) 1.73
b) 2.84
c) 0.87
d) 2.47
e) 1.51
Q14: Given the same data as above, the y-intercept, a, of the least squares regression line y = a +bx, is closest to:
a) 15.6
b) 7.3
c) 10.1
d) 2.2
e) 10.8

Can't seem to find anything in my textbook (Maths Quest) on how to solve those last two, thanks in advance.
EDIT: Ok, don't worry I figured out Q13+14, found the formula for it in another section of my notes, but still confused as to how I should go about answering Q12. =\

[iroflmfao]

should be a + - answer if thats all the information given...

[ech_93]

For Q13.... b (the gradient) =(r*s_y)/s_x and

for Q14..... a(y -intercept) = mean of y - ( b * mean of x)

[MicroShift]

Yeah that's what I eventually found in my notes book ech_93, cheers.

[Hodgeyhodgey]

Did you get any other information for Q12? If you have the equation instead of the graph you can see if it's a +/- gradient.

[MicroShift]

There were more words but no extra information, typical Further.

[Comatose]

is this question in the maths quest book? what pg?
type the whole question out if there were more words

[MicroShift]

Oh hold on, I think it's referring to a graph at the top of the page, but it looks like my teacher screwed up the photocopy a bit so it kind of cut off the part where it says "The following information relates the questions 11 and 12". The graph is clearly negative, so the answer would be a.