Que: How much force is required to lift the weight?

A) 40 lbs          

B) 50 lbs          

C) 60 lbs         

D) 70 lbs

Ans: (C) 
Solution: 60 lbs is needed to lift the weight. It can be calculated like this:

 f = (w x d1)/d2
 f = (80 x 9)/12
 f = (720)/12
 f = 60 lbs