Ratio And Proportion
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Ratio of a and b can be found by dividing a by b. written as a:b
Ratio has no unit
Ratio is expressed in simplest and lowest numbers eg 100:50 is better written as 2:1. Ratio never tells you the exact value of the numbers, which is very clear from the fact that 2:1 could be 100:50 or 50:25 or 4:2 or anything else as long as the condition is satidfied.
Find the following
1. Triplicate the ratio 5:4
2. Duplicate the ratio 2√5 : 5√2
3. The reciprocal of the ratio 1:2
1. Triplicate ratio is (5)3 : (4)3 = 125 : 64
2. Duplicating the ratio we get 20:50 = 2:5
3. Reciprocal is 2:1
Divide Rs 600 in 7:3
The first part is 7 times and second is 3 times. We call it 7x & 3x . The total so becomes 7x + 3x = 10x. But the total is 600. So 10x=600 or x=60.
So the first part is 7x=7*60=420. The second part similarly is 3x=3*60=180
You could have also got 180 by subtracting first part from total 600 like 600-420=180
The rule is that when you have number N to be divided in the ratios a:b:c:d
You get each part by dividing a or b or c or d by the rational sum (a+b+c+d) and multiplying by N
Like a’s share = [ a/(a+b+c+d) ] x N
Similarly you get other.
1. A certain amount was divided between Sahil and Rohan in the ratio of 4:3. If Rohan’s share was Rs 1200. What is the total amount ?
2. If a box contains 10 balls of red and white colour then which of these ratio of white is to red balls is not possible.
3. A sum of money is to be divided among P,Q and R in the ratio of 2:3:5. If the total share of P& R together is Rs800 more than Q what is the R share?
4. The marks obtained by Praveen and Vijay are in the ratio of 4:3 and those by Vijay and Suresh in 9:7. The marks of Praveen and Suresh are in the ratio of
5. The salary of A,B and C are in the ratio of 1:3:5, If B & C’s together salary is 24000, by how much percentage is B’s salary more than A?
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