Mathematics quiz on Speed and Work (20-08-2020)

Two bi-cycle riders started at a speed of 7m/s and 8 m/s on a circular path in opposite directions. If the perimeter of the circle is 300 metre then after what time will they meet first time?

Running at a uniform speed a train crosses 120 m long platform and 170-meter-long platform respectively in 12 sec and 16 sec. What is the speed of the train?

An ordinary and an express train are running in the same direction respectively at a speed of 30 km/h and 84 km/h on parallel tracks. The driver of the first train observes that the express train takes 15 sec to cross him. What is the length of express train?

A man walks for  hours at a speed of 6 km/h and later he walks 10 km in  hours. What is his average speed (in km/h) during entire journey?

A car covers a distance of 690 kms in 30 hours. What will be the average speed of the car?

A can complete a work in 45 hours. B and C can complete the same work in 60 and 36 hours respectively. If they all started working together and A leaves 15 hours before the completion of work then in how many days will the work be completed?

A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in :

A can do a work in 15 days and B in 20 days. If they work on it together for 4 days, then the fraction of the work that is left is :

Manoj can paint a mesuem in 20 days and Neeraj can paint it in 40 days. With help of Saurabh, they did the job in 10 days only. Then, 'Saurabh' alone can paint the museum in

‘A’ alone completes  part of a work in 20 days. The remaining work then completed by ‘A’ and ‘B’ working together in 3 days. How long would ‘B’ alone take to do two times the original work?