10 men can dig a well 50 feet deep in 8 days. How many men can dig a well 100 feet deep in 10 days?

Correct option is A

Given: 

10 men can dig a 50 feet deep well in 8 days.

how many men are required to dig a 100 feet deep well in 10 days. 

Concept Used: 

$$\frac{M_1D_1}{W_1}=\frac{M_2D_2}{W_2}$$   

Where, M = men , D = days, W = work 

​Solution:  

From the condition;

​$$M_1=10, W_1=50,D_1=8,M_2=x, W_2=100,D_2=10$$ 

So, applying the formula; 

$$\frac{10\times8}{50}=\frac{x\times10}{100}$$ 

​$$\frac85$$ = $$\frac{x}{10}$$ 

x = $$\frac{8\times10}5$$ 

x = 8$$\times$$2

x = 16 

Thus, men required are 16