Lottery Winnings

The parents won 12,000 euros. They decided to spend 34% of their winnings on Christmas presents and put the rest in the bank. How many euros did they deposit in the bank? What was the annual interest rate at the bank if they were credited with 118.8 euros in interest after one year?

Final Answer:

b =  7920 Eur
i =  1.5 %

Step-by-step explanation:

$$\begin{gathered} v=12000 \\ m=\frac{34}{100}\cdot v=\frac{34}{100}\cdot 12000=\frac{34\cdot 12000}{100}=\frac{408000}{100}=4080 \\ b=v-m=12000-4080=7920\text{Eur} \end{gathered}$$

$$\begin{gathered} x=118.8\text{Eur} \\ i=100\cdot \frac{x}{b}=100\cdot \frac{118.8}{7920}=\frac{3}{2}\%=1.5\% \end{gathered}$$

Try another example