Question 1:
The given formula is
[tex]I=\frac{PTR}{100}[/tex]
To make T, the subject we multiply both sides by 100:
[tex]100I=\frac{PTR}{100} \times 100[/tex]
This becomes
[tex]100I=PTR[/tex]
Divide both sides by PR
[tex]T=\frac{100I}{PR}[/tex]
b) Amanda's principal is , P=€2565
The interest rate is 3.5% p.a. that is R=3.5
We want to find how many years, her money will gain an interest of I=€718.20
We substitute into the formula for T,
[tex]T=\frac{100 \times 718.20}{2565 \times 3.5}[/tex]
This simplifies to:
T=8
Therefore it will take 8 years
2) Percentage profit
[tex] = \frac{profit}{cost \: price} \times 100\%[/tex]
The cost price of the 80 articles €200
The selling price is 3.5×80=€280
The profit =€280-€200=€80
The percentage profit is now
[tex] = \frac{80}{200} \times 100\%[/tex]
[tex] = 0.4 \times 100\%[/tex]
[tex]40\%[/tex]
The percentage profit is 40%
Question 3)
Let the original price of the calculator be x.
Then 85% of this price will be:
[tex] \frac{85}{100} \times x[/tex]
This is the same as€32.89
We equate and solve for x.
[tex] \frac{85}{100} x= 32.89[/tex]
[tex]0.85x = 32.89[/tex]
[tex]x = \frac{32.89}{0.85} [/tex]
[tex]x = 38.69[/tex]
The original price is €38.69
