1.  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?
A. 3.6%
B. 4.5%
C. 5%
D. 6%
E. None of these

Answer: Option E

Explanation:

Let the original rate be R%. Then, new rate = (2R)%.

Note:
Here, original rate is for 1 year(s); the new rate is for only 4 months i.e. year(s).

725 x R x 1 + 362.50 x 2R x 1 = 33.50
100 100 x 3

(2175 + 725) R = 33.50 x 100 x 3

(2175 + 725) R = 10050

(2900)R = 10050

R = 10050 = 3.46
2900

Original rate = 3.46%