Suresh for 2 years invested Rs. 500 in SBI. He also invested Rs. 300 in ICICI for 4 years. At the end he received Rs. 220 from both banks as simple interest. What must have been rate of interest?

10%

Principle -500 , 300, Time - 2, 4 years, SI = 220 (combined)

Formulae for SI = \(\frac{\text{P Χ R Χ T} }{ 100}\) 

Putting the values in the formulae:

According to the question:

220 = \(\frac{\text{500 Χ R Χ 2} }{ 100}\) + \(\frac{\text{300 Χ R Χ 4} }{ 100}\) 

220 = 10R + 12R

220 = 22R

R = 10%