Mathematics · Arithmetic Progressions · NCERT Examples
Example 9
A complete, independently verified solution for NCERT Example 9.
Change resourceExample 9
Mathematics · Chapter 5 · NCERT Examples
Verified NCERT questions and solutionsSolutions are checked independently and follow the supplied NCERT chapter edition.
NCERT Example
Example 9
₹1000 is invested at 8% simple interest yearly. Do yearly accumulated interests form an AP, and what is the interest after 30 years?
Solution
Board-exam working:
Simple interest for one year is PR/100=1000×8/100=₹80.
Therefore the accumulated interests are ₹80,₹160,₹240,… and each consecutive difference is ₹80, so they form an AP with a=80,d=80.
For 30 years, a₃₀=80+(30−1)80=80+29×80=80+2320=₹2400.
Check directly: PRT/100=1000×8×30/100=₹2400.
Final answer
Yes; d=₹80 and the 30-year interest is ₹2400.