Question

A sum of ₹725 is lent in the beginning of a year at a certain rate of interest. After 8 months, a sum of ₹362.50 more is lent but at the rate twice the former. At the end of the year, ₹33.50 is earned as interest from both the loans. What was the original rate of interest?

Options

• 3.6%

• 4.5%

• 5%

• 3.46%

Answer 1

3.46%
Explanation :
Let the original rate be r %.
Then, new rate = (2r)%
Here, the original rate is for 1 yr,
the new rate is for only 4 months i.e.`1/3`yr.

∴ `((725xxrxx1)/100)+((362.50xx2rxx1)/(100xx3))=33.50`

⇒  `(2175+725)r=33.50xx100xx3`

⇒ `(2175+725)r=10050`

⇒ `(2900)r=10050`

⇒  `r=10050/2900=3.46`

∴  Original rate = 3.46%