## Wednesday, June 8, 2011

### June Vacation Chap 9.2 RATE (L1) Rate in Everyday Situation

What's defined in Wikipedia: Rate (mathematics)
In mathematics, a rate is a ratio between two measurements, often with different units.[1]. If the unit or quantity in respect of which something is changing is not specified, usually the rate is per unit time. However, a rate of change can be specified per unit time, or per unit of length or mass or another quantity. The most common type of rate is "per unit time", such as speed, heart rate and flux. Rates that have a non-time denominator include exchange rates, literacy rates and electric flux.

When we describe the units of a rate, the word "per" is used to separate the units of the two measurements used to calculate the rate (for example a heart rate is expressed "beats per minute"). A rate defined using two numbers of the same units (such as tax rates) or counts (such as literacy rate) will result in a dimensionless quantity, which can be expressed as a percentage (for example, the global literacy rate in 1998 was 80%) or fraction or as a multiple.

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Rate is commonly used in our daily life. Here are some examples:

40 km/h - 40 kilometres per hour
30 steps/min - 30 steps in per minute
2 l/hour - 2 litres per hour
67 words/min - 60 words per 1 min
80 m/week - 80 metres per week
25km/l - 25 kilometres per 1 litre
\$90/m³ - \$90 per cubic metre

Think of 2 real life situations in which we use the concept of rate to describe useful information.

Here is an example:
The Singapore Flyer rotates at the rate of 0.24 m/s or 0.76 km/h

1. Like when you have a copy machine. You need to print 200 copies, and knows what rate the printer works at, so you know how long the job is going to take.
Or
The doctors need to check their patients' heart rate to make sure that they are not ill.

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3. During war, you need to know the RATE of which the enemies are advancing.
AND
When you are flying an aircraft (during descend in this case) you need to know the RATE of which your aircraft is descending at. (or you'll burst a few tyres)

4. 1. We use it when we found out the number of babies born per year which is the birth rate
2. We can use rate to judge how fast an object increases or decreases in price

5. 1. When you are driving a car, you need to know the amount of fuel needed for you to travel that specific distance. For example, if 1 litre of fuel is needed to travel a distance of 24km, then how much fuel is needed to travel 72 km. Like this, you will know how much fuel you need.
2.Rate can also be involved in exchange rates. Example from Singapore dollar to China yen, is about five times, so you roughly know how much an item in China cost.(convert the price to sg dollar)

6. 1. When a patient is admitted to the hospital because of severe injuries, the doctor would need to know the heart beat rate to know if the patient is breathing normally or is having trouble breathing.

2. When there is a natural disaster, for example a typhoon and it is heading towards a city, the people would have to know the rate that the typhoon is approcashing them so that they can prepare for it.

7. 1. When your Cameron you need to know at how fast will Ragul hug you.

2. When you are playing Assassin's Creed you will need to know how fast your target is running in order to catch up with him.

Disclaimer: Any similarities with anything living or dead is purely NON-COINCIDENTAL

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9. 1. When driving, you need to know the rate of which your car is consuming the petrol.

2. A group of construction workers are given a certain period of time to construct finish a HDB Flat. So they have to plan the rate of how much work needs to be done within the period to finish the construction.

10. 1.If we want to save the amount of electricity used we need to find the rate of the consumption of energy

2.When you are driving a car you need to know the rate at which you are travelling so you don't exceed the speed limit

11. 1. During an examination, you need to know how long you have to take for a mark, so you can finish the examination and also have time to check it within the given time.
2. When you are applying for a job to be a secretary or a personal assistant, the employer will want to know how many words you can type per minute.

12. In driving, you need to keep track of your rate of acceleration to aviod getting a ticket from the TP.
And, you need to see the rate of weather change (weather forecast) to avoid getting wet when you go out.

13. 1. When people drive cars, people need to know how fast the car is moving per kilometer/hour.

2. Everyday, people need to tell time, so they need to know the rate the Earth is orbiting the sun.

14. 1. We need to know the rate of the time we need to do a question in exam to make use of time the best we can.

2. We need to know the rate of how much force is needed to fly a plane.

15. 1. If you are getting paid by the hour, you would need to know the rate of how much your boss would pay you per hour. (eg \$8/hour)
2. When refilling petrol for a car at the petrol station, the person who is paying would need to know what is the how much it would cost for each litre.

16. 1.When running participating in a marathon, one must use rate in other to maintain speed in front of others and not get tired easily.

2.Driving a car also needs rate as to calculate the speed of it.

17. 1. Rate can also be used to find out how many times does the fan's blade spin in a minute, so that we could set it to the right amount of speed.

2. Rate can also be used to find out the speed of a vehicle and how much petrol it uses. So that we could save the petrol usage.

18. 1. We use rate to calculated the population in a country
2. Rate can be used to find the speed of a moving vehicle

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20. 1. When there is a hurricane, we have to know the speed per unit of which the wind is moving at. To know how serious the damage and harm that the wind can do to the environment as well as the people.

2. Rate is also used to find the rate of decrease of an airplane. The pilot needs to know how fast or slow is he decreasing in his altitude. So the pilot will not crash into the ground when flying at a low level.

21. In an airplane the pilot needs to know how fast is the plane travelling if not he might not reach the place he needs to get to in time or inorder not to plunge to a stall