1.

Rs. 1800 is invested at 4% per annum simple interest. If the interest is added to the principal after every 5 yr, the amount will become Rs. 2448 after?1). 14 yr2). 7 yr3). 18 yr4). \(8\frac{1}{3}\) yr

Answer»

<P>Rs. 1800 is INVESTED at 4% per annum simple interest.

The interest is added to the PRINCIPAL after every 5yr.

Formula of Simple interest = (P × R × T)/100 where P is the principal, R is the RATE of interest and T is the TIME period.

So, the simple interest in 5 years

= Rs. 1800 × 5 × (4/100) = Rs. 360.

New principal amount = Rs. 1800 + 360 = Rs. 2160

So, the interest in next duration = Rs. 2448 - 2160 = Rs. 288

Let the x years needed to have interest Rs. 288.

Now we can write,

2160 × x × (4/100) = 288

⇒ x = 28800/8640

⇒ x = 10/3

∴ The total years needed = 5 + (10/3) = 25/3 = $(8\frac{1}{3})$


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