- 4 years
- 5 years
- 6 years
- 7 years

Option 3 : 6 years

**Given:**

Monthly interest = Rs. 165

Rate of interest = 11% p.a

Amount = Rs. 29880

**Formula Used:**

Simple interest = (Principal × Rate × Time)/100

**Calculation:**

Let the sum invested be Rs. ‘P’

Rate of interest = 11%

Simple interest = (Principal × Rate × Time)/100

Monthly interest = (P × 11 × 1/12)/100 = 165

⇒ P = (165 × 1200)/11 = Rs. 18000

Now,

Let the sum amount to Rs. 29880 in ‘n’ years

Simple interest in n years = Amount – Principal = 29880 – 18000 = Rs. 11880

⇒ 11880 = (18000 × 11 × n)/100

⇒ n = 11880/(180 × 11)

⇒ n = 1080/180 = 6 years

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