Sharp EL-W531X Operation Manual page 16

Power and Radical root
<Example 2>
(1)
400000
5
(2)
100
5
300000
1
If the principal is a (¥), the annual interest rate is r (%),
and the number of years of interest accumulation is x (years),
the final amount y (¥) is given by the following equation:
(1) Find the final amount when a principal of ¥400,000 is
deposited for three years at an annual interest rate of 5%
and the interest is compounded annually.
(2) When a principal of ¥300,000 is deposited for five years
and the interest is compounded annually, the final amount is
¥339,422. The annual interest rate r is given by the equation below.
Find the annual interest rate r.
Operation
1
100
3
339422
15
y = a ( 1 + r / 100 )
(
y = 400000 1 +
(
y
x
r = 100 - 1
a
(
339422
5
r = 100
300000
Display
x
3
)
5
100
)
)
- 1