In a flower decoration the first row has (11) flowers and each next row has (3) more flowers. How many flowers are there in (10) rows?
Answer and explanation
Correct answer: 245
The numbers of flowers form an arithmetic progression with first term \(a=11\), common difference \(d=3\), and \(n=10\) rows. Thus, \(S_{10}=\frac{10}{2}[2(11)+(10-1)\times3]=5(22+27)=245\). Therefore, 245 is correct. A value such as 240 can result from using an incorrect last term or number of terms. Exam tip: In AP word problems, first identify \(a\), \(d\), and \(n\), then apply the formula for \(S_n\).
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What is the correct answer to this question?
245
Why is this the correct answer?
The numbers of flowers form an arithmetic progression with first term \(a=11\), common difference \(d=3\), and \(n=10\) rows. Thus, \(S_{10}=\frac{10}{2}[2(11)+(10-1)\times3]=5(22+27)=245\). Therefore, 245 is correct. A value such as 240 can result from using an incorrect last term or number of terms. Exam tip: In AP word problems, first identify \(a\), \(d\), and \(n\), then apply the formula for \(S_n\).
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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