Friday, May 10, 2013

How to Use Ratios


When two quantity of same unit are compared or divided, it is called as a ratio.  The ratio will give a relationship between the values in terms of the quantity.  Suppose Jason has $50 and Mike has $150.  Then the ratio of their money can be written as `50/150` = `1/3` `implies` 1: 3.  This shows that Mike is having an amount that is 3 times of Jason.



This concept will help in dividing certain values among some body else.

Now let us see few problems of this kind.

Example problems ratios:

Ex 1: The sum of the salaries of two persons A and B for a month is $8625.

Their salaries are in the ratio 25: 44.  Find their salaries.

Sol: The total sum is $8625.

Total ratio is 25 + 44 = 69

Therefore The salary for A is` 25/69 xx` 8625 = $3125.

The salary for B is `44/69 xx` 8625 = $5500.

Ex 2: Two numbers are in the ratio 7:17.  The first number is 441.

Find the second number.

Sol: Let the total value of the two numbers be x.  Total ratio is 7 + 17 = 24.

Given    :  `7/24 xx` x = 441

`implies` x = 441` xx 24/7` = 1512.

Therefore the second number is `17/24 xx ` 1512 = 1071.

More example problems on ratios:

Ex 3: Two groups A and B are of 850 is strength.  They are in the ratio 7:10. If  50 of them added to group A and some more to group B, the new ratio will be 8:13.  Find number added to B.

Sol: Given: The total is 850.

Ratio is 7:10

`implies` Total ratio is 7 + 10 = 17.

Therefore A group = `7/17 xx` 850 = 350

B group = `10/17 xx` 850 = 500

Now, also given, the new ratio is `[350+50] /[500 +x]` = `8/13` .

`implies ` 13(400) = 8 (500+x)

Therefore 5200 = 4000+8x

Therefore 8x = 5200 – 4000 = 1200

Therefore x = `1200/8` = 150.

Therefore 150 added to B.

Algebra is widely used in day to day activities watch out for my forthcoming posts on pre algebra tutorials and algebra 2 solver free. I am sure they will be helpful.

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