Answer:
r = 8%
Step-by-step explanation:
Given that,
Interest, I = $24
Principal, P = $1200
Time, t = 90 days = 90/360 = 1/4 years
We need to find the rate.
We know that,
The simple interest is given by :
[tex]I=\dfrac{Prt}{100}[/tex]
Put all the values,
[tex]r=\dfrac{100I}{Pt}\\\\r=\dfrac{100\times 24}{1200\times \dfrac{1}{4}}\\\\r=8\%[/tex]
So, the rate is 8%.