Answer:
Shorty has $142 after 7 month.
Step-by-step explanation:
The concept of compounded interest involves an initial capital that is reinvested month by month, it means that the initial capital plus the interest earned during the first month is reinvested on the second month and so on. The equation that describes the relationship between the final capital with the initial capital, the percentage of compounded interest and the time is:
Cf = Ci(1 + r)^n
where Cf: final capital (the money tha Shorty needs, $142)
Ci: initial capital (the money that Shorty has, $80)
r is the interest (9% = 0,09)
n: time (in months)
⇒142 = 80 (1 + 0,09)^n ⇒ 142/80 = (1,09)^n ⇒ 1.775 = (1,09)^n At this point you have to apply logarithms.
⇒ log (1.775) = n log (1.09) ⇒ n = log (1.775)/log (1.09) ⇒ n= 6.658
Shorty has $142 after 7 month.
