In a showroom, the sale of refrigerator increased from 10000 to 13310 in 3 years. Find the rate of increase in sale per annum.

Initial qty = 10000
Final Qty = 13310
Increased qty =13310-10000 = 3310
Time period = 3 years
Rate of increase per annum =Increased qty/ (Initial qty *Time period) * 100%
Rate of increase per annum =3310/ (10000*3) * 100% = 11.033%
Therefore rate increase in sale per annum = 11.033% (Answer)