A sweet shop sells (20) boxes on the first day and (4) more boxes each next day. How many boxes are sold on the (11)th day?
Answer and explanation
Correct answer: 60
The daily sales form an arithmetic progression (AP), with first term 20 and common difference 4. The 11th term is \(a_{11}=a+(11-1)d=20+10\times4=60\). Therefore, 60 boxes are sold on the 11th day. Choosing 56 would add the increase only 9 times, but there are 10 increases from the first day to the 11th day. Exam tip: use \(a_n=a+(n-1)d\) for the nth term.
Frequently asked questions
What is the correct answer to this question?
60
Why is this the correct answer?
The daily sales form an arithmetic progression (AP), with first term 20 and common difference 4. The 11th term is \(a_{11}=a+(11-1)d=20+10\times4=60\). Therefore, 60 boxes are sold on the 11th day. Choosing 56 would add the increase only 9 times, but there are 10 increases from the first day to the 11th day. Exam tip: use \(a_n=a+(n-1)d\) for the nth term.
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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