In the first (16) days, a student reads (1), (2), (3) pages respectively each day. How many pages will be read in total?
Answer and explanation
Correct answer: (136)
The daily readings form the natural-number sequence 1, 2, 3, ..., 16. Therefore the total is the sum of the first 16 natural numbers, not the product of the number of days and a constant daily amount. Use \(S_n=\frac{n(n+1)}{2}\). With n=16, \(S_{16}=\frac{16\times17}{2}=8\times17=136\) pages.
Thus option C is correct. Another way to check is to pair the first and last readings: 1+16=17, 2+15=17, and so on. There are 8 such pairs, giving \(8\times17=136\). The sequence increases by one page each day, so answers such as 126 or 144 do not match the required arithmetic-series total. The supplied answer and explanation are accurate.
Frequently asked questions
What is the correct answer to this question?
(136)
Why is this the correct answer?
The daily readings form the natural-number sequence 1, 2, 3, ..., 16. Therefore the total is the sum of the first 16 natural numbers, not the product of the number of days and a constant daily amount. Use \(S_n=\frac{n(n+1)}{2}\). With n=16, \(S_{16}=\frac{16\times17}{2}=8\times17=136\) pages.
Thus option C is correct. Another way to check is to pair the first and last readings: 1+16=17, 2+15=17, and so on. There are 8 such pairs, giving \(8\times17=136\). The sequence increases by one page each day, so answers such as 126 or 144 do not match the required arithmetic-series total. The supplied answer and explanation are accurate.
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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