The service cost of a vehicle is (2000) rupees in the first year and increases by (500) rupees each next year. What is the cost in the (5)th year?

Correct answer: ₹4000

The service costs form an AP with first term ₹2000 and common difference ₹500. The cost in the fifth year is \(a_5=a+(5-1)d=2000+4\times500=4000\). Hence, ₹4000 is correct. Choosing ₹4500 incorrectly counts 5 increases; from the first year to the fifth year, there are only 4 increases. Exam tip: use \(a_n=a+(n-1)d\) for the nth term of an AP.