A sum of Rs. 1000 is invested at 8% simple interest per year. Calculate the interest at the end of each year. Do these, interests form an A .P. ? If so, find the interest at the end of 30 yrs.
Here, P = 1000, r = 8%
Interest at the end of first year.
Interest at the end of second year
Interest at the end of third year
So, we have 80, 160, 240, ..............
Here, a = 80, d = 80
Therefore, interest at the end of 30 yrs. i.e. a30 is,
a30 = a + (30 –1) d = 80 + 29 x 80
= 80 + 2320 = 2400
So the interest at the end of 30 years is Rs. 2400.