SSC MTS 6 Aug 2019 Shift 1 Paper

Compound interest = principal × [(1 + r/100)‌2 - 1]
⇒ Compound interest = 3000 [(1 + 20/100)2 - 1] = 3000[(36/25) - 1] = 3000 × 11/25
⇒ Compound interest = Rs. 1320
∴ The compound interest for 2 years is Rs. 1320.
Alternate Solution:
Rate = 20% = 1/5

Compound interest = 600 + 600 + 120 = Rs. 1320