Chapter 11.7, Problem 25HP

To determine

To calculate the diameter of a home object − outer diameter of a jar lid.

Answer to Problem 25HP

  $220$ millimeters

Explanation of Solution

Given information:

On measuring the outer diameter of a jar lid, it was found to be $d=70$ millimeters.

Formula used:

Circumference (c) of a circle can be calculated using formula $2\times \pi \times r$

Where ‘r’ is the radius $=\frac{d}{2}$

For calculations, value of $\pi =\frac{22}{7}$ .

Calculation:

Since the outer diameter of the jar is $d=70$ , radius $r=\frac{d}{2}$ .

On putting the value, radius is found to be

  $=\frac{70}{2}$

Or,

  $=35$ millimeters.

  $c=2\times \pi \times r$

Formula of the circumference of a circle.

  $=2\times \frac{22}{7}\times 35$

Putting the value of the radius in the formula and simplifying.

  $=10\times 22$

On multiplying the expression.

  $=220$ millimeters.

This number has been verified by measuring the outer circumference with a measuring tape.