Travel problems

In your book, Maths Mela (Chapter 1), we read how people travel, now and then: on foot, on horseback, by cycle, motorbike, train, ship, aircraft and even spacecraft. A person on a cycle can usually cover about 12 to 20 km in an hour.

A cyclist covers 15 km in one hour. If she keeps the same speed, how far does she go in 4 hours? Each hour she covers another 15 km: 15 + 15 + 15 + 15 = 60 km. That is 4 × 15 = 60 km.

A school has 461 girls and 439 boys, and all of them are going on a trip. First find how many children there are: 461 + 439 = 900 children. Now, how many vehicles are needed? It depends on how many seats each vehicle has.

A car has 4 seats. How many cars carry 900 children? We need the number that makes 900 when it is multiplied by 4. 4 × 200 = 800, and 4 × 25 = 100 more, so 4 × 225 = 900. We need 225 cars. An aeroplane with 180 seats is much bigger: 180 + 180 + 180 + 180 + 180 = 900, so just 5 aeroplanes carry everyone.

The more seats a vehicle has, the fewer vehicles we need. The children need 450 bicycles of 2 seats, 90 tempo travellers of 10 seats, 36 minibuses of 25 seats, and only 5 aeroplanes of 180 seats.