Correct Answer: 12% p.a.
Explanation:
If the interest earned is 25% more than the earlier interest then the rate of interest also should be 25% higher than the earlier rate. 
 Let the earlier rate of interest be x%. 
 Now it will be (x + 3)% 
 % increase = (x + 3) - x/x * 100 = 25
 => x = 12%
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