Simple interest: the formula, the amount and the comparison with compound interest

PYQ (2016-2025 papers)

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Free questions

1. Question 1

   The difference between the compound and simple interest on a sum at 2% a year for 2 years is ₹1. What is the principal?

   1. A. ₹50
   2. B. ₹250
   3. C. ₹5000
   4. D. ₹2500
   Answer and explanation

   ✓ Correct answer: D. ₹2500

   For two years C.I − S.I = P(r/100)²: P × (2/100)² = 1, so P × 0.0004 = 1 and P = ₹2500.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (விடைகள் (பயிற்சி 4.3), p. 286 (PDF p. 292))

2. Question 2

   What is the formula for simple interest I? (P principal, N years, R annual rate)

   1. A. I = PNR
   2. B. I = PNR/100
   3. C. I = P(1 + R/100)ᴺ
   4. D. I = 100PN/R
   Answer and explanation

   ✓ Correct answer: B. I = PNR/100

   Simple interest I = PNR/100, where P is the principal, N the number of years and R the annual rate.

   Source: கணக்கு, எட்டாம் வகுப்பு, தமிழ் வழி (Mathematics, Standard VIII, Tamil medium; Samacheer Kalvi) (இயல் 4 வாழ்வியல் கணிதம் (4.4 கூட்டுவட்டி), p. 139 (PDF p. 145))