A cloth shop sells (35) metres of cloth on the first day and (5) metres more each next day. How many metres of cloth are sold on the (10)th day?
Answer and explanation
Correct answer: 80 metres
The daily sales form an arithmetic progression (AP), with first term \(a=35\) and common difference \(d=5\). Sales on the 10th day are \(a_{10}=a+(10-1)d=35+9\times5=80\) metres. Choosing \(85\) metres incorrectly counts 10 increases instead of 9. Exam tip: for the \(n\)th term of an AP, add \(n-1\) common differences.
Frequently asked questions
What is the correct answer to this question?
80 metres
Why is this the correct answer?
The daily sales form an arithmetic progression (AP), with first term \(a=35\) and common difference \(d=5\). Sales on the 10th day are \(a_{10}=a+(10-1)d=35+9\times5=80\) metres. Choosing \(85\) metres incorrectly counts 10 increases instead of 9. Exam tip: for the \(n\)th term of an AP, add \(n-1\) common differences.
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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