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## What is profit and loss?

The amount of money you pay for something is: cost price.

The amount of money you get for sell something is: selling price.

Selling price is greater than the cost price: you get a profit.

Profit = selling price – Cost price

Selling price is less than the cost price: It gives loss.

Loss = Cost price – Selling price

How to find Ratio?

Ratio: to compare two quantities by division.

The quotient of that division is called a ‘ratio’.

The colon ‘:’ is used to express a ratio.

The ratio of 7 to 9 is written as ‘7:9’

The ratio of 7 to 9  is read as ‘7  is to 9’.

The ratio  is written as ‘a:b’ and is read as ‘a is to b’.

Let us understand this better by example:

In a cricket match, Max scored 80 and Sam scored 40 runs.

Let us see how many times Max’s score is that of Sam’s.

Just divide Max’s score by Sam’s

Max’s score/  Sam’s score=   80/40 =  2/1= 2:1

Thus,we find here that,  Max’s score is 2 times Sam’s score. More

Volume of the cylinder

How to calculate the volume of a cylinder?

Volume of cylinder = area of base × height

Example: The radius of the base of a cylinder is given 28 cm and its height is 20 cm.

Find the volume of this cylinder.

Here,

Radius r =28cm

Height h = 20 cm

Volume of cylinder
= area of base × height

= 22/7× 28× 28× 20

= 22 × 4 × 28× 20

= 49280 cu cm

Example:

The height of a cylindrical tank is 1 m

and its diameter is 84 cm.

How many liters of water can it hold?

(1000 cu cm = 1 liter)

Here, r = 84/2= 42 cm

H = 1 m = 100 cm

Volume of tank   = ?

Volume of cylinder
= area of base × height

= 22/7× 42 × 42 × 100

= 22 × 6 × 42 × 100

= 554400 cu cm

1000 cu cm = 1 liter

554400 cu cm = 554400 /1000 liters= 554.400 liters

The tank will hold   554.400 liters of water.  Learn more

Evaluate each expression

A)   Rule 1: x1= x.

Example:

(1/2)4 x (5/2)-2

you see that when base raised to the positive power value;

x= x.

So that,

(1/2)4 = ½ × ½ × ½ × ½

(5/2)-2= 2/5 × 2/5(reciprocal of the number)

So that,

(1/2)4 x (5/2)-2
= ½ × ½ × ½ × ½ × 2/5 × 2/5

Multiply numerators and multiply denominators

= 1/100

B)   Rule 2:- When base raised to the negative power value; x-1 = 1/ x1

Any number with an exponent of 0 (except 0) automatically equals 1

Example:-

(7/12)0 ×4-1

(7/12)0 = 1 and

4-1= 1/4

Therefore,

(7/12)0 ×4-1

= 1 × 1/4

=   1/4  (Multiply numerators and multiply denominators)

### 2 Comments »

1. John G. Gellner, FRIC, C.Sci., C.Chem. says:

Could I be involved in your program? I am 88 years old, more or less housebound and live in the Philippines. I taught Chemistry, Physics and Maths in schools and technical colleges in Britain until I was 55, then worked for three years for the Saudi Arabian government as supervisor for a group of hearing-impaired adolescents and came here in 1985 as a VSO volunteer to work in science education. About three years ago I had an attack of ARDS (Acute Respiratory Distress Syndrome) which prevented me from my ambulatory work with schools and colleges here and left me desperately in need of work. Not of income – my pensions suffice for my family’s needs. It seems to me that online work might be the solution to my problem, which is the reason for my contacting you.

John G. Gellner

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