Question

A lamp can stay lit up to 5 hours when 500 mL of kerosene is loaded in it. How long will it keep burning if there's only 125 mL left? ​

Answer 1

The lamp will keep burning for 1.25 hours (or 1 hour and 15 minutes) with 125 mL of kerosene.

Explanation:

We can use the proportional reasoning method to solve the problem.

The amount of kerosene and the time the lamp stays lit are directly proportional. This means that the ratio of the amount of kerosene to the time the lamp stays lit is constant.

Let's call this constant of proportionality "k". Then we have:

k = amount of kerosene / time the lamp stays lit

We can use this constant to solve the problem.

First, we can find k:

k = 500 mL / 5 hours = 100 mL/hour

This means that the lamp consumes kerosene at a rate of 100 mL per hour.

To find how long the lamp will stay lit with 125 mL of kerosene, we can set up a proportion:

500 mL / 5 hours = 125 mL / x hours

where x is the number of hours the lamp will stay lit with 125 mL of kerosene.

We can cross-multiply to solve for x:

500 mL * x = 5 hours * 125 mL

500x = 625

x = 1.25 hours