Small interest 3

Tomáš had a certain amount of money in his account, which earned him €64 in interest for a year at an interest rate of 2% p. a. What would be the interest on the same amount if the annual interest rate was 3.5%?

Correct answer:

u₂ =  112 Eur

Step-by-step explanation:

$$\begin{gathered} u_1=64\text{eur} \\ {r}_1=2\%=\frac{2}{100}=\frac{1}{50}=0.02 \\ {r}_2=3.5\%=\frac{3.5}{100}=0.035 \\ {u}_1=r_1\cdot a \\ a=u_1/r_1=64/0.02=3200\text{eur} \\ {u}_2=r_2\cdot a=0.035\cdot 3200=112\text{Eur} \end{gathered}$$

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