Math Problem Statement
Solution
Let's carefully analyze the problem and solve it step by step:
We are told that the marks scored by A, B, C, and D are in geometric progression (GP). Let's denote their marks as:
where is the first term and is the common ratio of the GP.
Step 1: Relationship between marks of C and sum of A and B
It is given that the marks scored by C are 30% less than the sum of the marks scored by A and B. This can be mathematically written as:
First, convert % into a decimal:
Thus, the relation becomes:
Simplifying:
Step 2: Solving the quadratic equation
Expand and rearrange:
We can solve this quadratic equation using the quadratic formula: where , , and .
Substitute the values:
Thus, the two possible values for are:
Since the common ratio in a geometric progression should be positive, we take .
Step 3: Percentage comparison of marks between D and B
Now, we want to find what percentage the marks scored by D are more than the marks scored by B. The marks scored by D are and the marks scored by B are . The percentage increase is given by:
Substitute :
Thus, the marks scored by D are 56.25% more than the marks scored by B.
Conclusion:
The answer is .
Would you like more details on any part of this explanation?
Here are some related questions:
- How is a geometric progression defined and used in solving problems?
- Can you explain more about the quadratic formula and its application here?
- How does the concept of percentage increase work in real-life problems?
- What are the properties of geometric progressions that help in calculating ratios between terms?
- How do you handle decimal percentages like in problems?
Tip: In geometric progression, the ratio between any two consecutive terms remains constant, which makes it easy to model growth or decay situations.
Ask a new question for Free
By Image
Drop file here or Click Here to upload
Math Problem Analysis
Mathematical Concepts
Geometric Progression
Percentage Calculations
Quadratic Equations
Formulas
C = (A + B) * (1 - 30 5/9%)
r^2 - 0.6945r - 0.6945 = 0
Percentage Increase = (r^3 - r) / r * 100
Theorems
Quadratic formula
Suitable Grade Level
High School