Question
A heater uses 3 units of electricity in 40 minutes. How many units does it consume in 2 hours?
Solution
In 40 minutes, electricity used = 3 units.
In 1 minute, electricity used = 3/40 units.
In 120 minutes (2 hours), electricity used = 3/40 × 120 = 9 units
Thus, the heater consumed 9 units of electricity in 2 hours.
(9 is the answer)