1981 年

The running speeds of three boys $A$, $B$ and $C$ are in the ratios $a:b:c$. The times that $A$, $B$ and $C$ take to complete a $1500\text{ m}$ race are in the ratios

If $n$ is a positive integer, which of the following numbers is/are odd? I. $2^{2n+1}$ II. $3(2^n)$ III. $(2n+1)^2$

A factory employs $x$ workers each working $n$ hours a day. The whole factory produces $k$ watches per day. If $y$ workers go on leave, then how many hours a day should the remaining workers work in order to produce the same number of watches per day?

The daily wages of a man and a boy are in the ratio $2:1$. In a day a man has to work $8$ hours but a boy only $6$ hours. The hourly wages of a man and a boy are in the ratio

In the figure, $\angle BAC=90^\circ$, $AB=8$, $AC=5$ and $AX\perp BC$. $BCDE$ is a rectangle with $CD=AX$. What is the area of the rectangle $BCDE$?

The height of the cone in the figure is $h$. It contains water to a depth of $\dfrac{1}{2}h$. $\dfrac{\text{Volume of water}}{\text{Capacity of the cone}}=$

The figure above represents a $50\text{ m}\times20\text{ m}$ swimming pool. The pool is in the shape of a prism with a rectangular surface and four vertical walls. The dimensions of the sidewall $ABCDEF$ are as shown in the figure. What is the capacity of the pool in $\text{m}^3$?

Given that $\sin\theta-\cos\theta=\dfrac{1}{2}$, what is the value of $\sin\theta\cos\theta$?

If $0^\circ\le\theta\le360^\circ$, the minimum value of $1+2\cos\dfrac{\theta}{2}$ is

The figure above shows the graph of