All solutions here are SUGGESTED. Mr. Teng will hold no liability for any errors. Comments are entirely personal opinions.
Let and denote the total time A & B take respectively, in seconds.
For A: Time taken
For B: Time taken
Difference (nearest seconds)
- Be careful of the units, its in seconds.
- Be careful to write in sets.
- Be careful when you’re rounding off (ii) as you need to round off according to the range of values. If you rounded down to 63.8, this means you accept 63.81, which is out of range and will cause him to arrive before 1.5H. I reckon this part will get many students who are less careful. :/