Thank you so much sir! Bt l hv a question though… The formula says y= a+bx bt on the example in the lecture you subtracted, like the formula changed to y=a- bx. Would you mind to explain why?

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Rufus. says

sir , for correcting variable “a” we had to multiply by 1000 , but for b why did we not multiply by 100

sir please explain !!

John Moffat says

Y was written in 1,000’s. X was written in 100’s.

So a was multiplied by 1,000 and b was multiplied by 1,000/100 = 10.

wiseoleowl says

I just can’t see how b came to be negative for the formula to be changed from y=a + bx to

y = a – bx.

John Moffat says

I should have written + and not –

Sorry 馃檨

It is typed correctly in the answers printed in the free lecture notes.

wiseoleowl says

Noted. Thanks Sir Moffat.

Tsits says

Thank you so much sir! Bt l hv a question though… The formula says y= a+bx bt on the example in the lecture you subtracted, like the formula changed to y=a- bx. Would you mind to explain why?

artipha says

I was about to post on the last part of the equation but John has answered it, thank you.

opentuition_team says

We are pleased you found it 馃檪

atheef55 says

What is the Interpolation and extrapolation?

John Moffat says

Interpolation is forecasting within the range of the observations. Extrapolation is forecasting outside the range of the observations.

lbasusi says

Thank you John!

John Moffat says

You are welcome 馃檪

egret says

In the 15″56,I suppose it should be y=a+bx,but it’s y=32.8572-6.7857x,is it right?

John Moffat says

Sorry – it should be a plus and not a minus!!

I must re-record it (but the printed answer in the lecture notes is correct 馃檪 )