Answer:
10%
The investor will be credited with the interest at the rate of 10%.
Explanation:
Cap on interest rate which is going to be credited = 10%
Participation=80%
Increase in reference index = 15%
As the participation rate is 80% so the investor can credit the amount of 80% * 0.15= 12% (15% of 80%) but as it is given in the question, the cap of 10% is put on the interest rate credited so the investor will be credited with the interest at the rate of 10%.