A SUV has 4 tyres and 1 spare tyre. Each tyre can travel a maximum distance of 20,000 km before wearing off. What is the maximum distance the car can travel before the owner is forced to buy a new set of tyres?
A SUV has 4 tyres and 1 spare tyre. Each tyre can travel a maximum distance of 20,000 km before wearing off. What is the maximum distance the car can travel before the owner is forced to buy a new set of tyres?
The correct option is C 25,000 km
Divide the lifetime of the spare tyre into 4 equal part i.e., 5000 and swap it at each completion of 5000 km distance.
Let four tyres be A, B, C and D and spare tyre be S.
0-5000 km: Use A, B, C and D for driving.
5000-10,000 km: Replace A with S.
10,000-15,000 km: Put A back to its original position and replace B with S
15,000-20,000 km: Put B back to its original position and replace C with S
20,000-25,000 km: Put C back to its original position and replace D with S
∴ After 25,000 km all the tyres including the spare one will need replacement.
25,000 km
Divide the lifetime of the spare tyre into 4 equal part i.e., 5000 and swap it at each completion of 5000 km distance.
Let four tyres be A, B, C and D and spare tyre be S.
0-5000 km: Use A, B, C and D for driving.
5000-10,000 km: Replace A with S.
10,000-15,000 km: Put A back to its original position and replace B with S
15,000-20,000 km: Put B back to its original position and replace C with S
20,000-25,000 km: Put C back to its original position and replace D with S
∴ After 25,000 km all the tyres including the spare one will need replacement.
