Rakib invested 10000 Tk. in two 5 years term. He received 5% for the first term and 8% for the second term. What is the average rate of interest did he received?

Question: Rakib invested 10000 Tk. in two 5 years term. He received 5% for the first term and 8% for the second term. What is the average rate of interest did he received?

Solution:
in first term, he received = 10000 × 5 × 5%
= 2500 Tk.
in second term, he received = 10000 × 5 × 8%
= 4000 Tk.
so,
total interest after 10 years, I = 6500
P = 10000
n = 10
r = ?

we know,
I = Pnr/100
r = 100I / Pn
= 650000/(10000 × 10)
= 6.5%