Question : Three persons P, Q, and R run along a circular track at speeds of 3 km/hr, 4 km/hr, and 6 km/hr respectively. If the length of the track is 36 km, then how much time will they meet again at the starting point?
Option 1: 38 hours
Option 2: 36 hours
Option 3: 24 hours
Option 4: 28 hours
Correct Answer: 36 hours
Solution : Speed = $\frac{\text{Distance}}{{\text{Time}}}$ The time it takes for each person to run one lap is: For P: $T_P = \frac{36}{3} = 12 \text{ hours}$ For Q: $T_Q = \frac{36}{4} = 9 \text{ hours}$ For R: $T_R = \frac{36}{6} = 6 \text{ hours}$ The time at which they all meet again at the starting point is the least common multiple (LCM) of $T_P$, $T_Q$, and $T_R$. The LCM of 12, 9, and 6 hours is 36 hours. Hence, the correct answer is 36 hours.
Result | Eligibility | Application | Selection Process | Cutoff | Admit Card | Preparation Tips
Question : Amit and Sumit start walking from the same point in opposite directions at speeds of 6 km/hr and 4 km/hr, respectively. How far will they be from each other after 4 hours?
Question : A train crosses two persons travelling at 4 km/hr and 6 km/hr in the same direction in 12 sec and 14 sec, respectively. The speed of the train is ________.
Question : A boat covers 24 km upstream and 36 km downstream in 6 hours, while it covers 36 km upstream and 24 km downstream in $6\frac{1}{2}$ hours. The speed of the current is:
Question : A boy goes from home to school at a speed of 30 km/hr and returns back at a speed of 70 km/hr. What is his average speed for the journey?
Question : If a truck moves at a constant speed of 30 km/hr for 1 kilometre and 45 km/hr for the next 1 kilometre. What is the average speed of the truck?
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile