The circumference of a circle is $251.2 \, cm$. Find its diameter. $(\pi = 3.14)$ (in $cm$)

The diameters of front and rear wheels of a tractor are $80 \,cm$ and $2 \,m$ respectively. Find the number of revolutions that the rear wheel will make in covering a distance in which the front wheel makes $1400$ revolutions.

The length of minor $\widehat{AB}$ of a circle is $\frac{1}{4}$th of its circumference,then the measure of the angle subtended by minor $\widehat{AB}$ at the centre will be $\ldots .$ (in $^{\circ}$)

Four circular cardboard pieces of radii $7 \, cm$ are placed on a paper in such a way that each piece touches the other two pieces. Find the area of the portion enclosed between these pieces (in $cm^2$).

In the figure,a circle is inscribed in a square of side $5 \, cm$ and another circle is circumscribing the square. Is it true to say that the area of the outer circle is two times the area of the inner circle? Give reasons for your answer.

The length of a minor arc of a circle is given by the formula $\ldots \ldots \ldots \ldots$