Comparing Quantities-grade 08



Ratios

Ratios can be use to compare quantities. Example. If we have 5 orange and 20 apple the we can write the ratio 5:20. If we want to write the ratio of apple and orange the it will write as 20:5. The ratio is writing respectively.

Ratio as fraction

The ratio can also write as in terms of fractional number. Here the first ratio will come as numerator and and the second ratio will come as denominator. So in our previous example we can write the ratio of orange and apple is 5:20  = 5/20.

If we are saying the ratio of orange and apple is 5:20, that means if there is 5 orange then there is 20 apple. The ratio will always write as simplest form. So 5:20 will write as 1:4. That means there will be 1 orange for 4 apple. Like this we can compare the quantity.

Ratio as percentage

From the ratio we can find the percentage of quantities.For example. 5 orange and 20 apple can write as 5/20. now we will make the denominator as 100. then it will become (5×5)/(20×5)= 25/100.  So the percentage of orange is 25%. (that means there will be 25 orange when apple is 100). We can also find the fraction by unitary method  like ( 5/20)x100  = 500/20= 25%.

Finding the increase or decrease percentage

To find the increase percentage of thing, for example. The price of a scooter was 34000 in last year. if the price increased by 20 % what will be the price of the scooter this year.

Method -1: Here first we will find the 20% of the current price and then add that to the existing price then we will get the new price.

(20/100) x 34000 = 6800

increased price = 34000+6800= 40800

Method2: Unitary method.  (120/100)*34000 =40800 ( here the 120 = 100% + the increased 20% =120%)

To find the decrease  percentage of thing, for example. The price of a scooter was 34000 in last year. If the price decreased by 20 % what will be the price of the scooter this year. Here also we can find the 20% of the current price and can subtract the amount form the current price, then we will get the present price.

In unitary method we can find the 80 % of the current value (because the decreased percentage is 20%). which is (80/100)*34000.

finding discounts

Discount is the difference of the actual price(MRP) and the sales price.

Discount= market price- sales price.

If an item Have the market price 840 and it is selling at 714 then

Discount = 840-714=126.

we can also find the discount % by

Discount %= (discount amount / market price) *100.

(remember (% /100)*total=value)

We can also find the discount amount if the discount % is given by

Discount amount= (discount%*market price)/100.

 

 

 

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