can someone check if the second thingy in there is right?

you enter x and y coordinates of two points and it gives you the slope (y=mx+b)

i'm not entirely sure i got b (y intercept) formula correct, can someone check?

ignore the other stuffs

also can .xls be allowed?

G16 should actually be "=G6-G15" or else you get the negative of it.  You could have checked this by actually making a graph and plotting the points to see that the y intercept had to be positive

EDIT: The third thing seems to be an interest formula except I don't think you did it right, you should add the last value, not the initial value and the interest should be fixed (or just write it in the form of a geometric progression....).

i forgot i had a graphic calc

o well, thnx =]

edit:

this is a partner activity, and i did the first 2 parts and someone else did the 3rd. thnx for noticing, now i get to scold them tomorrow

also, how do i do the geometric thingy? i rarely use excel and hardly know how to do anything

For excel you should write "=$N3*1.01^R" but you will need to change the R for each (increase by one each time) and I even made it so you can put it into one and drag it across with ease too

EDIT: I should explain it to.... $N3 is you initial value, 1.01 is the interest rate and keeping the principle amount and you times that by the time interval as this is the same as just putting another *1.01 on the end to get the next interval.  If you do them individually and then substitute each equation in to the next then you would see exactly what I'm talking about.