If the letters have usual meanings, the formula for finding compound interest, compounded yearly for the given time is :

$2\dfrac{1}{2}$ years :

1. $P\Big(1 + \dfrac{r}{100}\Big)^{\dfrac{5}{2}} - P$

2. $P\Big(1 + \dfrac{r}{100}\Big)^{\dfrac{5}{2}}$

3. $P\Big(1 + \dfrac{r}{100}\Big)^2\Big(1 + \dfrac{r}{200}\Big)$

4. $P\Big(1 + \dfrac{r}{100}\Big)^2\Big(1 + \dfrac{r}{200}\Big)$ - P

When interest is compounded half-yearly then the formula for C.I. for the given time is :

1 year :

1. $P\Big(1 + \dfrac{r}{200}\Big)^2 - P$

2. $P\Big(1 + \dfrac{r}{100}\Big)^2 - P$

3. $P\Big(1 + \dfrac{r}{200}\Big)^2$

4. $P\Big(1 + \dfrac{r}{100}\Big)^2$

When interest is compounded half-yearly then the formula for C.I. for the given time is :

2 years :

1. $P\Big(1 + \dfrac{r}{100}\Big)^2 - P$

2. $P\Big(1 + \dfrac{r}{200}\Big)^2 - P$

3. $P\Big(1 + \dfrac{r}{200}\Big)^4 - P$

4. $P\Big(1 + \dfrac{r}{100}\Big)^4 - P$

If ₹ 6000 earns C.I. = ₹ 1200 in 6 months; then the rate of interest per year is :

1. 40%

2. 15%

3. 20%

4. 24%