百分數與變分

If $2x=3y=5z$, then $x:y:z=$

Two men cycle round a circular track which is $3\text{ km}$ long. If they start at the same time and at the same spot but go in opposite directions with speeds $6\text{ km/h}$ and $9\text{ km/h}$ respectively, for how long must they cycle before they meet for the first time?

A man marks his goods at a price that will bring him a profit of $25\%$ on the cost price. If he wants to sell his goods to a friend at the cost price, the percentage discount on the marked price should be

The scale of a map is $1:20\,000$. On the map the area of a farm is $2\text{ cm}^2$. The actual area of the farm is

It took Paul $40$ minutes to walk from Town $A$ to Town $B$. If the return journey took him $30$ minutes, the percentage increase in his speed was

A merchant sold $2$ articles each at $\$1000$. For the first article, he gained $25\%$ on the cost price. For the second article, he lost $20\%$ on the cost price. Altogether

Three numbers are in the ratio $2:3:5$. The ratio of their average to the largest of the three numbers is

What will $\$P$ amount to in 3 years' time, if interest is compounded monthly at 12% per annum?

A child spent $\dfrac{1}{10}$ of his saving on a shirt and $\dfrac{1}{5}$ of his savings on a pair of trousers. He then spent 30% of the rest of his savings on books. What percentage of his saving did he spend altogether?

The rent of a flat is raised by 30% every two years beginning from a fixed date. Counting from that date, after how many years will the rent just exceed twice the original rent?