9.10 Revenue and Distance

A train traveled 240 kilometers at a certain speed. When the engine was

replaced by an improved model, the speed was increased by 20 km/hr and the

travel time for the trip was decreased by 1 hour. What was the rate of each


A factory tests the road performance of new model cars by driving them at two

different rates of speed for at least 100 kilometers at each rate. The speed rates

range from 50 to 70 km/hr in the lower range and from 70 to 90 km/hr in the

higher range. A driver plans to test a car on an available speedway by driving

it for 120 kilometers at a speed in the lower range and then driving 120

kilometers at a rate that is 20 km/hr faster. At what rates should he drive if he

plans to complete the test in 3(1/2) hours?

An athlete plans to row upstream a distance of 2 kilometers and then return

to his starting point in a total time of 2 hours and 20 minutes. If the rate of

the current is 2 km/hr, how fast should he row?

A man bought a number of articles at equal cost for 500. He sold all but two

for 540 at a profit of 5 for each item. How many articles did he buy?

A merchant bought some pieces of silk for 900. Had he bought 3 pieces more

for the same money, he would have paid 15 less for each piece. Find the

number of pieces purchased.

A clothier bought a lot of suits for 750. He sold all but 3 of them for 864

making a profit of 7 on each suit sold. How many suits did he buy?

A merchant bought a number of barrels of apples for 120. He kept two barrels

and sold the remainder at a profit of 2 per barrel making a total profit of 34.

How many barrels did he originally buy?

A number of men subscribed a certain amount to make up a deficit of 100

but 5 men failed to pay and thus increased the share of the others by 1 each.

Find the amount that each man paid.

The rate of the current in a stream is 3 km/hr. A man rowed upstream for 3
kilometers and then returned. The round trip required 1 hour and 20 minutes.
How fast was he rowing?

A dealer bought a number of sheep for 440. After 5 had died he sold the

remainder at a profit of 2 each making a profit of 60 for the sheep. How

many sheep did he originally purchase?