The speed of a train varies inversely with its length. A 200 meters long train runs at a speed of 60 km/hr. In how much time will a 500 meters long train cover 96 km?

3, 18, 48, 93……….?............

A circle with radius 42 cm is drawn. What will be length of arc of a sector subtending an angle of 60 degrees at the Centre?

255, 366, 479, 684, ?

313, 623, 933, 1234, ?

2, 9, 30, ?, 436, 2195, 13182

6, 42, ?,  1260, 5040, 15120, 30240

5, 54, 90, 115, 131, 140?