Answer: He would need
pounds to fill the container all the way.
Explanation:
Since we have given that
Fraction of mashed potatoes he had to fill up a container =

Fraction of mashed potatoes he ended up using =

So, we need to find the number of pounds that he would need to fill the container all the way.
So, number of pounds would be

Hence, he would need
pounds to fill the container all the way.