A sum of Rs. 10,000 is lent partly at 6% and the remaining at 10% p.a. If the yearly interest on the average is 9.2%, the money lent at 10% is:-

Let the amount at 6% be x
Amount at 10% be (10000 –x)
At 9.2 % interest, SI = 10000 X 9.2 X 1/100 = 920
Amount = 10920
⇒ 6x/100 + (10000 – x)10/100 = 920
⇒ 6x – 10x + 100000 = 92000
⇒ 4x = 8000
⇒ x = 2000
Money lent at 10 % = 10000 – 2000 = 8000