### 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. We use rate to describe useful information when it comes to speeding and accident happened.The rate eg. speed,is the most crucial part of the case to prove the defendant guilty or innocent.
We use rate to describe information when we want to buy houses.We see how much does it cost per square metre and see if it is worth it.This can help us compare with other flats and would be able to help us save some money.

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3. We use rate to describe information like how fast a person can type using: words/h

We use rate to describe the flow of water from a tank which comes out quite often in Math Problems, using cm*3 or litres.

4. litres per second or minute.

5. We use rate when we try to find out how fast a car is moving compared to another car: km/h

We use rate to find out how fast a train can go in order to be in time for our appointment.

Yi De 06

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7. We can use speed to find out how fast or slow a moving object is moving. Like the world's fastest train travels at 574.8 km/h.

We can also use it when we are buying houses by finding out how much per square foot cost. Like the selling prices of The Tennery ranged from S\$950 to S\$1,300 per square foot.

8. We can use rate when are running for our NAPHA or similar events as we can calculate our speed using rates and compare them to see if we have improved or deproved.

We can also use rate to calculate how fast our battery in our Learning Device runs out, so we can estimate when to use it or when to dim our screen to save batteries.

9. We can use rate when we are counting a crowd in an event. For example, we can count the crowds every 10 mins. So we can find out the amount of people coming in and do the necessary preparations.

We can also use it to calculate the rainfall of certain areas, so we can predict whether floods or droughts will come and do the necessary preparations.

10. We can use rate, for example: A scaled model of a tyrannosaurus can be used to predict its actual mass with information about its actual length.

We can also use rate, for example: Movie screens are created to handle film with specific dimensions. Suppose the width of each film cell is 5.48 cm and the height is 2.30 cm. An ideal movie screen would show the entire picture without cropping out any of the sides. In order to project the film perfectly on the screen, a proportion/rate comparing the height and width needs to be used so that the correct height of the screen can be accurately determined.

11. We can use rate to, in a restaurant, calculate the time taken for a cook to cut fruits, vegetables or meat so that preparations can be finished on time.

We can also use rate to calculate the amount of energy a power plant can generate.

12. We can use rate to find out the time taken for a falling man to hit the ground so that we can find out the best time to open our parachutes.

We can use rate to find out how much time is needed for a plant to grow. therefore we know when we can harvest it.

wei siew

13. 1.We use rate to estimate how much water we use and how much it costs. \$/litre

2.We use rate to find the difference in the distance while walking and running. m/s

14. We can use rate to find patterns in real life, for example if you want to find out how many times a 1-year-old baby cries in 2 mins.

We can also use rate to find out a situation of a patient, be it breaths per minute etc.

15. Rate is commonly being used in record setting universally.(For Example...*OMG THIS GUY CAN EAT 20 HOTDOG BUNS IN 30 SECONDS!* Or something like that.)

Rate is also used to estimate accurately a event that is about to happen. (The speed of two cars approaching each other and using that to find out when they will collide.)

16. We can use rate to find out how fast will water leak from a dam assuming there is a leak allowing rescue workers to evacuate people in time.

We can use rate to find out how fast a missle travels and when it will hit the intended target.

17. We can use rate to find out how many frames is needed to create animations. For example, 24 frames/sec or 24 frames per second is needed to create a simple animation. 30 frames/second or 30 frames per second are for simple games.

We can use rate for estimating the human population. For example, experts could say that 1 person is dying every second and 3 people are born every second in this country. Then, we could say that the population is increasing by 2 person per second.

18. When the Police is going to fine a vehicle owner, they look at the rate the car is moving at, then they will fine the vehicle owner if it exceeds the speed limit regulations!
For example, 40km/hour

Rate is also used in video editing. Certain videos are 30 fps or 24 fps and most videos are 25 fps. and fps stands for Frames per Second.

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20. Rate can be used to describe how fast the printer prints paper using pieces/minute.
Eg. 100pieces/min
Rate can be used to measure how fast water moves during floods .
Eg. 50km/sec

21. We can use rate to calculate the number of cups of water one can drink in a minute. Example, 3 cups per minute.

Rate can also find out the number of times one can blink in a minute. Eg. 60 blinks per minute.

Nina

22. We can use it in sports, for example to calculate the speed of a smash during a game of badminton. Example: 250km/h-->speed of the smash

We can also use it to calculate the number of pages of a book read in a minute. Example: 7 pages per minute

23. We can use rate to calculate the number of words you can type in a minute.
For e.g. 20words/min

We can also use it to calculate the speed of a car.
For e.g. 100km/h

24. Rate can used for calculating birth and death "speed" of a country to see if the population is decreasing or increasing.
Eg. 1800 people died in this year. 1800 people / year.

Rate can also be used for amount of water or electricity used in a month for the bills.

Eg. 43l/month. 43 litres of water is used in a month.

Owen here.

25. Rate can be used to find out the Rpm(rounds per minute) a wheel spins
EG. 50Rpm
Rate can be used to find out the rate of something that is growing
EG. A teenager grows at a rate of 5cm per year