(a) A dealer sold a car to a man and made a profit of 15%.

MATHEMATICS
WAEC 2006

(a) A dealer sold a car to a man and made a profit of 15%. The man then sold it to a woman for N120,175.00 at a loss of 5%. How much did the dealer buy the car?

(b) The diameter of the wheel of a car is 36cm. How many revolutions, correct to three significant figures, will it make to cover a distance of 1.05 km? [Take \(\pi = \frac{22}{7}\)].

Explanation

(a) Let the cost of the car to the dealer be x.

Sales of car to a man with 15% profit : (115% of x = 1.15 x\)

Sale of the car to the woman by the man at 5% loss : (95% of 1.15x = N120,175.00)

\(0.95 \times 1.15x = N120,175.00\)

\(1.0925x = N120,175.00\)

\(x = \frac{120,175.00}{1.0925}\)

\(x = N110,000\)

The original cost of the car to the dealer = N110,000.00.

(b) Circumference of a circle = \(2\pi r\)

Distance covered by the wheel = 1.05 km

Radius of the wheel = 18cm

Circumference of the wheel = \(2 \times \frac{22}{7} \times 18\)

= \(113.14 cm\)

Note : 1.05 km = 105,000 cm

Number of revolution = \(\frac{105,000}{113.14}\)

= \(928.05 revs\)

\(\approxeq 928 revs\)



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