Three rings complete 60, 36 and 24 revolutions in a minute. They start from a certain point in their circumference down wards. By what time they come together again in the same position?

A student walks from his house at speed of $2\frac{1}{2}$ km/hour and reaches his school late by 6 min. Next day, he increases his speed by 1 km/hour and reaches 6 min before school time. How far is the school from his house?

A boy covers a certain distance on a toy train. If the train moved 4 kmph faster, it would take 30 minutes less. If it moved 2 kmph slower, it would have taken 20 minutes more. The distance is

Two persons A and B start from the same point to travel from Chandigarh to Ambala. The distance between Chandigarh and Ambala is $60 \text{ km}$. Speed of A is $4 \text{ km/hr}$ slower than B. B, when reaches Ambala, starts back via the same route without taking any rest and meets A who was still $12 \text{ km}$ away from Ambala. Find the speed of A.

Ram and Shyam run a race between points $A$ and $B, 5 \mathrm{~km}$ apart. Ram starts at 9 AM from A at a speed of $5 \mathrm{~km} / \mathrm{hr}$, reaches $B$ and returns to $A$ at the same speed. Shyam starts at $9: 45 \mathrm{AM}$ from $\mathrm{A}$ at a speed of $10 \mathrm{~km} / \mathrm{hr}$, reaches $B$ and comes back to $A$ at the same speed.

At what time do Ram and Shyam meet each other ?

Ram and Shyam run a race between points $A$ and $B, 5 \mathrm{~km}$ apart. Ram starts at 9 AM from $A$ at a speed of $5 \mathrm{~km} / \mathrm{hr}$, reaches $B$ and returns to $A$ at the same speed. Shyam starts at $9: 45 \mathrm{AM}$ from $\mathrm{A}$ at a speed of $10 \mathrm{~km} / \mathrm{hr}$, reaches $B$ and comes back to $A$ at the same speed.

At what time does Shyam overtake Ram ?

In a flat race, A beats B by 15 m and C by 29 m. When B and C run over the same course together, B wins by 15 m. The length of the course is