21) Sagar fires two bullets from the same place at an interval of 12 minutes but Sameer sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first. What is the approximate speed of train (if sound travels at the speed of 330 metre per second)?
(a) 660/23 m/s
(b) 220/7 m/s
(c) 330/23 m/s
(d) 110/23 m/s
22) A boat sails downstream from point A to point B, which is 10 km away from A, and then returns to If the actual speed of the boat (in still water) is 3 km/h, the trip from A to B takes 8 hours less than that from B to A. What must the actual speed of the boat for the trip from A to B to take exactly 100 minutes?
(a) 1 km/h
(b) 2 km/h
(c) 3 km/h
(d) 4 km/h
Good Luck!!