What is 20% of the sum of the first 150 natural numbers?
Answer and explanation
Correct answer: 2265
The sum of the first 150 natural numbers is S_150=150×151/2=75×151=11325. The governing percentage concept is that 20% equals 20/100=1/5. Therefore 20% of the sum is 11325×1/5=2265. Hence option C is correct. It is important to calculate the complete sum before applying the percentage; using 20% of 150 or forgetting the division by 2 would produce unrelated values. The result can also be checked as 11325×20/100=226500/100=2265, confirming the answer.
Frequently asked questions
What is the correct answer to this question?
2265
Why is this the correct answer?
The sum of the first 150 natural numbers is S_150=150×151/2=75×151=11325. The governing percentage concept is that 20% equals 20/100=1/5. Therefore 20% of the sum is 11325×1/5=2265. Hence option C is correct. It is important to calculate the complete sum before applying the percentage; using 20% of 150 or forgetting the division by 2 would produce unrelated values. The result can also be checked as 11325×20/100=226500/100=2265, confirming the answer.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Sum of first n natural numbers.
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