Economics Calculus

[zzehri]

Hello,
dC/dI = marginal propensity to consume. 1-marginal propensity to consume = marginal propensity to save. I differentiated the function, but upon inputting 25 as income, I got a different answer from the textbook. I am hoping to see if this is an error with my calculations, or with the textbook (the textbook is old and has a lot of errors).

Regards,
Zarah Zehri

 

[skeeter]

Show what you calculated and how you did it ... maybe someone can confirm your work as correct or point out any error.

 

[JeffM]

Marginal propensity to consume is not [MATH]\dfrac{dC}{dI}.[/MATH]
It is [MATH]\dfrac{dC}{dY}.[/MATH]