JAMB 2018 Mathematics · Question 40

A car uses one litre of petrol for every 14km. If one litre of petrol cost N63.00, how far can the car go with N900.00 worth of petrol?

Options

A.420Km
B.405Km
C.210Km
D.200Km

Answer: D. 200Km

Explanation written with AI and checked against the answer key

Analysis

To solve this problem, we need to determine how many litres of petrol can be purchased with N900.00 and then calculate the total distance the car can cover based on its fuel efficiency (14 km per litre).

Concept

This is a unitary method problem. We follow two main steps:

Find the total volume of fuel: Divide the total money available by the cost per litre.
Find the total distance: Multiply the total volume of fuel by the distance the car travels per litre.

Step-by-Step Solution

Step 1: Calculate the total litres of petrol bought. Total money = N900.00 Cost per litre = N63.00

\text{Total litres} = \frac{\text{Total money}}{\text{Cost per litre}}

\text{Total litres} = \frac{900}{63}

To simplify this fraction, we can divide both numbers by 9:

\frac{900 \div 9}{63 \div 9} = \frac{100}{7} \text{ litres}

Step 2: Calculate the total distance. The car travels 14 km for every 1 litre.

\text{Total distance} = \text{Total litres} \times \text{Distance per litre}

\text{Total distance} = \left( \frac{100}{7} \right) \times 14

Now, simplify the calculation:

\text{Total distance} = 100 \times \left( \frac{14}{7} \right)

\text{Total distance} = 100 \times 2

\text{Total distance} = 200 \text{ km}

Conclusion

Based on the calculation, the car can travel 200 km.

Note: Upon reviewing the calculation, the result is 200 km, which matches option D.

Exam Tip

When dealing with fractions in JAMB, try not to convert them to decimals immediately (like 14.28...). Keep them as fractions until the very last step. You will notice that the numbers often cancel out perfectly, making your work much faster and reducing the risk of calculation errors!

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