Answer:
Explanation:
Future value after 24 months = 1200
present value = 1000
Let monthly rate of interest = r
1000 = 1200/( 1+r )²⁴
( 1+r )²⁴ = 1200/1000
( 1+r )²⁴ = 1.2
taking log on both sides
24 log( 1+r ) = log 1.2
24 log( 1+r ) = .07918
log( 1+r ) = .003299
( 1+r ) = 1.007625
r = .007625
monthly rate of interest in percent = .7625%
II Option
Future value after 24 months = 1220
present value = 1020 - 20 = 1000
Let monthly rate of interest = r
1000 = 1220/( 1+r )²⁴
( 1+r )²⁴ = 1220/1000
( 1+r )²⁴ = 1.22
taking log on both sides
24 log( 1+r ) = log 1.22
24 log( 1+r ) = .086359
log( 1+r ) = .003598
( 1+r ) = 1.008319
r = .008319
monthly rate of interest in percent = .8319%
b )
Effective annual rate of uncle = (1.007625)¹² -1
= 1.09543 - 1 = .09543
In percent = 9.543 %
Effective annual rate of greedy friend = ( 1.008319)¹² -1
= 1.1045 -1
= 10.45 %
c ) The first one is cheaper so it is preferable.