A sweet shop sells (25) boxes on the first day and (5) more boxes each next day. How many boxes are sold in (7) days?
Answer and explanation
Correct answer: \(280\)
The daily sales form an arithmetic progression with first term \(a=25\), common difference \(d=5\), and \(n=7\) terms. Thus, \(S_7=\frac{7}{2}[2(25)+(7-1)5]=\frac{7}{2}(80)=280\). Therefore, \(280\) boxes are sold in 7 days. \(285\) results from using an incorrect number of terms or common difference. Exam tip: identify \(a\), \(d\), and \(n\) before applying the AP sum formula.
Frequently asked questions
What is the correct answer to this question?
\(280\)
Why is this the correct answer?
The daily sales form an arithmetic progression with first term \(a=25\), common difference \(d=5\), and \(n=7\) terms. Thus, \(S_7=\frac{7}{2}[2(25)+(7-1)5]=\frac{7}{2}(80)=280\). Therefore, \(280\) boxes are sold in 7 days. \(285\) results from using an incorrect number of terms or common difference. Exam tip: identify \(a\), \(d\), and \(n\) before applying the AP sum formula.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Word problems based on APs.
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