JAMB 2022 Mathematics · Question 35
What will be the result obtained when the numerator of is decreased by 37.5% and its denominator decreased by 20%.
Options
- A.1.5
- B.
- C.
- D.0.5
Answer: A. 1.5
Explanation written with AI and checked against the answer key
1. Analyze the question
We are given the fraction . We need to:
- Decrease the numerator (96) by 37.5%.
- Decrease the denominator (50) by 20%.
- Calculate the new fraction and simplify it to find the result.
2. Explain the concept
To decrease a value by a percentage, you subtract that percentage of the value from the original value.
- Formula: New Value = Original Value - (Percentage Original Value)
- Alternatively, you can multiply the original value by . For example, a 20% decrease means the new value is 80% of the original.
3. Show the solution
Step 1: Calculate the new numerator The original numerator is 96. We decrease it by 37.5%.
- Decrease amount =
- New numerator =
Step 2: Calculate the new denominator The original denominator is 50. We decrease it by 20%.
- Decrease amount =
- New denominator =
Step 3: Form the new fraction and simplify
- New fraction =
- Simplify by dividing both by 20:
- Convert to decimal:
4. Identify the answer
Comparing our result (1.5) with the given options, it matches option A.
5. Exam Tip
When dealing with percentage decreases, remember that "decreasing by " is the same as multiplying by .
- For the numerator: .
- For the denominator: . This method is often faster and less prone to subtraction errors during the exam!
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