Quantitative Aptitude · Averages, Ratios & Percentages
Ratio and Proportion — Questions & Answers
Ratio questions split a total into parts, combine chained ratios, or scale one quantity with another. Introduce a common multiplier k so each share becomes a real number.
- 5 solved questions
- Step-by-step AI walkthroughs
- Key formulas included
Key formulas
If a:b:c, the shares of total T are a+b+caT, and so on
Combine a:b and b:c by scaling to a common b, giving a:b:c
In a proportion a:b=c:d, the product of the means equals the product of the extremes: bc=ad
5 solved Ratio and Proportion questions
₹360 is divided between A and B in the ratio 4 : 5. What is B's share?
Solution — answer C
There are 4+5=9 parts, each worth 360÷9=40. B receives 5×40=Rs200.
3 steps · reveal one at a timeStep 1: Calculate Total Parts
The amount is divided between A and B in the ratio 4:5. To find out how many 'shares' or parts there are in total, we need to add the ratio numbers together. This gives us the total number of equal parts.
Step 2: Determine Part Value
The total amount to be divided is ₹360. We found there are 4+5=9 total parts. Now, divide the total amount by the total number of parts to find the value of one single part. This tells us how much money each part represents.
Step 3: The answer
So the answer is (C) ₹200. B's share is 5 parts of the total. Since each part is worth ₹40, B receives 5×40=Rs200.
If a:b=3:4 and b:c=8:9, what is a:c?
Solution — answer A
Make b the same in both ratios: a:b=6:8 and b:c=8:9, so a:c=6:9=2:3.
5 steps · reveal one at a timeStep 1: Understand the Ratios
We are given two ratios: a:b=3:4 and b:c=8:9. Our goal is to find the ratio a:c.
Step 2: Align Common Term
To find a direct ratio between a and c, we need to standardize the common term, b. This means making the value of b the same in both given ratios.
Step 3: Adjust First Ratio
In a:b=3:4, b is 4. In b:c=8:9, b is 8. To make b equal to 8 in the first ratio, we multiply both parts by 2. This gives a:b=(3×2):(4×2)=6:8.
Step 4: Combine and Simplify
Now we have a:b=6:8 and b:c=8:9. Since the value of b is now 8 in both, we can see that a:c=6:9. This ratio can be simplified by dividing both parts by their greatest common divisor, 3. So, 6:9=(6÷3):(9÷3)=2:3.
Step 5: The answer
So the answer is (A) 2 : 3. This is the simplified ratio of a to c after making the common term b consistent.
Two numbers are in the ratio 5 : 7. If 12 is added to each, the ratio becomes 3 : 4. What is the smaller number?
Solution — answer C
Let the numbers be 5x and 7x. Then 7x+125x+12=43, so 20x+48=21x+36 and x=12. The smaller number is 5×12=60.
4 steps · reveal one at a timeStep 1: Represent the numbers
Let the two numbers be 5x and 7x. This uses a common multiplier x to represent their actual values, maintaining their initial ratio of 5:7.
Step 2: Formulate the equation
When 12 is added to each number, the new ratio becomes 3:4. We can write this as an equation: 7x+125x+12=43.
Step 3: Solve for the multiplier
Cross-multiply to solve for x: 4(5x+12)=3(7x+12). This simplifies to 20x+48=21x+36. Subtracting 20x and 36 from both sides gives x=12.
Step 4: The answer
The smaller number is 5x. Substitute x=12 into 5x to get 5×12=60. So the answer is (C) 60, which is the smaller of the two numbers.
The ratio of two numbers is 3 : 5 and their sum is 96. By how much does the larger number exceed the smaller?
Solution — answer A
With 8 parts summing to 96, each part is 12. The numbers are 36 and 60, so the larger exceeds the smaller by 60−36=24.
5 steps · reveal one at a timeStep 1: Understand the Ratio
We are given two numbers in the ratio of 3:5. This means the first number can be represented as 3x and the second as 5x. Their sum is given as 96.
Step 2: Calculate Total Parts
The ratio 3:5 tells us there are 3+5=8 equal parts in total. Since the sum of the two numbers is 96, these 8 parts together equal 96.
Step 3: Value of One Part
To find the value of one part, we divide the total sum by the total number of parts. So, each part is worth 96÷8=12.
Step 4: Find the Numbers
Now we can find the actual numbers. The smaller number is 3×12=36. The larger number is 5×12=60. We have our two numbers.
Step 5: The answer
So the answer is (A) 24. The question asks by how much the larger number exceeds the smaller, which is 60−36=24.
₹782 is divided among three people in the ratio 21:32:43. What is the first person's share?
Solution — answer B
Clear the fractions by multiplying each part by 12: the ratio becomes 6:8:9 (23 parts). Each part is 782÷23=34, so the first share is 6×34=Rs204.
4 steps · reveal one at a timeStep 1: Simplify the Ratio
The given ratio is 21:32:43. To make it easier to work with, we need to remove the fractions. Find the least common multiple (LCM) of the denominators (2, 3, 4), which is 12.
Step 2: Convert to Whole Numbers
Multiply each part of the ratio by the LCM, 12. This gives us (12×21):(12×32):(12×43), which simplifies to 6:8:9. This is the ratio of shares.
Step 3: Calculate Share Value
The total number of parts in the simplified ratio is 6+8+9=23 parts. The total amount is ₹782. So, each part is worth 782÷23=34 rupees.
Step 4: The answer
So the answer is (B) ₹204. The first person's share corresponds to 6 parts in the ratio. Therefore, the first person's share is 6×34=Rs204.
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