Question

A severe weather siren in a local city can be heard within a radius of 1.3 miles. If the mayor of the city wants a new siren that can cover double the area of the old siren, what should the radius of the new siren be? (Round to the nearest tenth of a mile.)

Answer 1

radius = 1.3

area covered = pi x radius(squared)

= 3.142 x 1.3 x 1.3

= 5.31 mi square

double of this area = 5.31 x 2 = 10.62 mi square

if area = 10.62 .....what is radius ?

area = pi x radius squared

10.62 = 3.142 x r2

10.62 / 3.142 = r2 ( it means radius squared )

r2 = 3.38

take square root on both sides :

r ( square of r will be cut by square root )

and square root of 3.38 = 1.84

so after square on both sides : r = 1.84 mi

so radius to cover area of 10.62 mi square will be 1.84 mi.

HOPE IT HELPED !!!!!!