Great lecture sir, and thanks for the logics behind the equations and the graph support while explaining.

Sir, I did not understand why at the end you divided by X, ie in 100s , when infact x was to be multiplied . It was y= a + ‘bx’ not b/x. So it should be 1000 x 100. Instead of 1000/100.

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?

Asif110 says

Great lecture sir, and thanks for the logics behind the equations and the graph support while explaining.

Sir, I did not understand why at the end you divided by X, ie in 100s , when infact x was to be multiplied . It was y= a + ‘bx’ not b/x. So it should be 1000 x 100. Instead of 1000/100.

Please explain more clearly this part.

Thanks

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.

Asif110 says

I’m sorry, I don’t get the arithmetic.

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.

Mitiksha says

I have the same question. Variable B unit cost is in 100’s but it was multiplied by 10 instead of 100?

John Moffat says

See my answer above.

fatimasalim says

sir, but why are we doing that?

I don’t understand, please explain further.

John Moffat says

You do not need to do it. I only did it to keep the numbers smaller and so speed up the arithmetic.

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 🙁

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 🙂

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 🙂

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 🙂 )