1982 年

The marked price of a book is $\$240$. If the book is sold at a discount of 20%, the profit will be 20% of the cost price. What is the cost price of the book?

A right circular cone of altitude $3r$ and base radius $r$ has the same volume as a cube of side $x$. $x=$

Some air escapes from a spherical balloon of volume $a^3$. The balloon keeps its spherical shape and is now of volume $b^3$. What is the percentage decrease in the radius?

Coffee $A$ and coffee $B$ are mixed in the ratio $1:2$. A profit of 20% on the cost price is made by selling the mixture at $\$36$/kg. If the cost price of $A$ is $\$12$/kg, what is the cost price of $B$?

$(\sin\theta+\cos\theta)^2-1=$

If $\tan x=-\dfrac{3}{4}$ and $x$ is an angle in the second quadrant, what is the value of $\sin x+\cos x$?

If $A+B=180^\circ$, which of the following is/are true? I. $\sin A=\sin B$ II. $\cos A=\cos B$ III. $\tan A=\tan B$

From the top of a lighthouse, $h$ metres high, the angle of depression of a boat is $20^\circ$. How far is the boat from the base of the lighthouse, which is at sea-level?

In the figure, $OAB$ is a right-angled triangle in a horizontal plane with $\angle AOB=90^\circ$. $OC$ is a vertical line. If $OB=r$, $AC=$

In a circle, the angle of a sector is $30^\circ$ and the radius is $2\text{ cm}$. The area of the sector is