百分數與變分

It is given that $y$ is partly constant and partly varies directly as $x$. When $x=2$, $y=17$ and when $x=4$, $y=11$. Find the value of $x$ when $y=5$.

The marked price of a car is $50\%$ higher than the cost. If the car is sold at a $20\%$ discount on the marked price, then the percentage profit is

A sum of $\$14\,000$ is deposited at $4\%$ per annum for $5$ years, compounded yearly. Find the interest correct to the nearest dollar.

Let $x$, $y$ and $z$ be non-zero numbers. If $x:y=1:2$ and $y:z=3:1$, then $(x+y):(y+z)=$

It is given that $x$ varies directly as $y$ and inversely as $z^2$. If $y$ is decreased by $10\%$ and $z$ is increased by $20\%$, then $x$ is decreased by

The scale of a map is $1:8\,000$. If the area of a park on the map is $2\text{ cm}^2$, then the actual area of the park is

Peter sold two flats for $\$999\,999$ each. He lost $10\%$ on one and gained $10\%$ on the other. After the two transactions, Peter

Let $x$ and $y$ be non-zero numbers. If $2x-3y=0$, then $(x+3y):(x+2y)=$

If $z$ varies directly as $y^2$ and inversely as $x$, which of the following must be constant?

The marked price of a book is $20\%$ above the cost. If the book is sold at a $10\%$ discount on the marked price, then the percentage profit is