Rates Constant rates Here are some examples of

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Rates Constant rates Here are some examples of constant rates…… 50 mph 14 litres/min

Rates Constant rates Here are some examples of constant rates…… 50 mph 14 litres/min 7 m/s 50 miles travelled in 1 hour 14 litres flowed in 1 minute 7 metres travelled in 1 second

Example There are two taps in a yard. The first took 6 minutes to

Example There are two taps in a yard. The first took 6 minutes to fill an 84 litre tank. The second took 7 minutes to fill a 105 litre tank. Which tap is faster? To answer this, we need to find the rate of flow of each tap. We need to find the amount which comes out of each tap in 1 minute = ? litres Rate of flow will be in litre/min

Tap 1 6 minutes 84 litres 1 minute litres Rate of flow of tap

Tap 1 6 minutes 84 litres 1 minute litres Rate of flow of tap 1 is 14 litre/min Tap 2 7 minutes 105 litres 1 minute litres Rate of flow of tap 2 is 15 litre/min The second tap is faster

Exercises Calculate the rate of flow of these taps in litres/min, correct to the

Exercises Calculate the rate of flow of these taps in litres/min, correct to the nearest whole number 1. A tap which fills a 40 litre drum in 4 minutes. 2. One which fills a 600 litre tank in 9 minutes. 3. One which takes 17 minutes to fill a 200 litre tank. 4. 4. One which takes 4· 5 minutes to fill a 30 litre drum Answers 1. 10 litre/min 2. 67 litre/min 2. 3. 12 litre/min 4. 7 litre/min

5. A fire engine’s hose delivers water at 3500 litre/min. How much water does

5. A fire engine’s hose delivers water at 3500 litre/min. How much water does it deliver in 15 minutes? 6. A freshwater spring takes 7· 5 minutes to fill a 2· 5 litre bottle. What is the rate of flow of the spring in litre/min?

7. Water comes out of a tap at the rate of 14 litre/min. 8.

7. Water comes out of a tap at the rate of 14 litre/min. 8. (a)Copy an complete this table showing the amount of water which comes out at different times. Time in minutes 0 0· 5 1 1· 5 2 3 4 5 Amount in litres (b) Draw a graph of (time, amount) (c) Use the graph to find the time this tap will take to fill a tank which can hold 50 litres.

8. What is the rate of flow in each of these graphs?

8. What is the rate of flow in each of these graphs?

Problems 1. An aircraft travelling at a constant speed took 23 seconds to fly

Problems 1. An aircraft travelling at a constant speed took 23 seconds to fly 5000 metres. What was its speed in m/s, to the nearest whole number? 2. A machine making plastic tubing spews out 97· 5 metres of tubing in 15 seconds. At what rate does the tubing come out of the machine?

3. If £ 15 is worth the same as $19, work out the exchange

3. If £ 15 is worth the same as $19, work out the exchange rate between the £ and the $ (to 2 d. p. ) 4. (a) in $ per £ 5. (b) in £ per $

4. A typist is paid £ 99 for 36 hours work. What is the

4. A typist is paid £ 99 for 36 hours work. What is the rate of pay per hour? 5. Calculate the average speed of a train which travels from London to Edinburgh (305 miles) in 6· 4 hours.

Key Stage 4 Number Book Pages 23 & 24 COPY AND ANSWER THE FOLLOWING

Key Stage 4 Number Book Pages 23 & 24 COPY AND ANSWER THE FOLLOWING QUESTIONS. 11 TO 40 SHOW CLEARLY YOUR WORKINGS.