Two trains started at $7$AM from the same point. The first train travelled north at a speed of $80$km/h and the second train travelled south at a speed of $100$ km/h. The time at which they were $540$ km apart is ________ AM.

The distance between Delhi and Agra is $233$ km. A car $P$ started travelling from Delhi to Agra and another car $Q$ started from Agra to Delhi along the same road $1$ hour after the car $P$ started. The two cars crossed each other $75$ minutes after the car $Q$ started. Both ... car $Q$. How many kilometers the car $Q$ had travelled when the cars crossed each other? $66.6$ $75.2$ $88.2$ $116.5$

An automobile travels from city A to city B and returns to city A by the same route. The speed of the vehicle during the onward and return journeys were constant at $60$ km/h and 90 km/h, respectively. What is the average speed in km/h for the entire journey? $72$ $73$ $74$ $75$

The radius as well as the height of a circular cone increases by $10\%.$ The percentage increase in its volume is ________. $17.1$ $21.0$ $33.1$ $72.8$

In a country of $1400$ million population, $70\%$ own mobile phones. Among the mobile phone owners, only $294$ million access the Internet. Among these Internet users, only half buy goods from e-commerce portals. What is the percentage of these buyers in the country? $10.50$ $14.70$ $15.00$ $50.00$

Trunks ($10$ m long) and cars ($5$ m long) go on a single lane bridge. There must be a gap of at least $20$ m after each trunk and a gap of at least $15$ m after each car. Trunks and cars travel at a speed of $36$ km/h. If cars and trunks go alternately, what is the maximum number of vehicles that can use the bridge on one hour? $1440$ $1200$ $720$ $600$