If 28 men can finish a work in 15 days, 21 men can finish the same work in___________?

A. 24 days
B. 14 days
C. 15 days
D. 20 days
✅ The correct answer is option D. 20 days.
Time and Men are inversely proportional. Time taken by 28 men to finish the work = 15 days Time taken by a man to finish the work

= 15*28 days Time taken by 21 men = (15*28)/21 = 20 days

A person walking at 5/6th of his usual speed is 40 minutes late to his office. What is his usual travel time to his office?

A. 3 hours 20 minutes
B. 3 hours 15 minutes
C. 3 hours 30 minutes
D. 3 hours
✅ The correct answer is option A. 3 hours 20 minutes.
Let his usual speed be x kmph, the distance to his office be y km and his usual travel time be t hrs. y = xt = (5/6)x * (t+(40/60)) Solving the equation,

t = 3.33 hrs = 3 hrs 20 minutes