The circumference of the wheels of a truck is $440\, cm .$ They make $250$ rotations per minute. Then, the speed of the truck is $\ldots \ldots \ldots \ldots km / h$.
The length of square $ABCD$ shown in the diagram is $42\, cm .$ The shaded design is formed by drawing semicircles on all the sides of the square. Find the area of the shaded design. (in $cm^2$)
The wheel of a motor cycle is of radius $35\, cm$. How many revolutions per minute must the wheel make so as to keep a speed of $66\, km / h ?$
In a circle with radius $21 \,cm$, the length of a minor arc is $33 \,cm .$ Find the measure of the angle subtended at the centre by this arc. Also find the area of the minor sector and the minor segment formed by it.
If the radius of a circle is increased by $10 \%,$ then the corresponding area of new circle will be $\ldots \ldots \ldots . . .$