Correct answer is: c) 3 days

Explanation

6 hours per day a mason can build a wall in 4 days.
\therefore 1 hour per day a mason can build a wall =\left(4\times6\right) days.
\therefore 8 hours per day a mason can build a wall =\large\left(\frac{4\times6}{8}\right) days.
\rightarrow 3 days.
Ans: A mason will take 3 days to complete the wall working at the rate of 8 hours per day.

Rules of Three Method Explanation

Hours and Days are Inversely Proportional
\therefore\;8\;:\;6\;:\;:\;4\;:\;x
\rightarrow\large\frac{8}{6}=\frac{4}{x}
\rightarrow 8x=6\times4
\rightarrow x=\large\frac{6\times4}{8}
\rightarrow x=3
Ans: A mason will take 3 days to complete the wall.

Other versions of this specific math question are:

1. If a mason can complete a wall in 4 days, working 6 hours per day, how many days will it take him to finish the wall if he works 8 hours per day?
2. How many days will it take for a mason, who typically works 6 hours a day to build a wall in 4 days, to complete the same wall if he increases his daily working hours to 8?
3. Given that a mason finishes building a wall in 4 days by working 6 hours each day, how many days will it take for him to complete the wall if he extends his daily working hours to 8?
4. If a mason completes a wall in 4 days with 6 hours of work each day, how many days will he take to complete the same wall when he increases his daily working hours to 8?
5. Suppose a mason takes 4 days to construct a wall while working 6 hours daily. How many days will he need to complete the wall if he extends his daily working hours to 8?