Areas

1

Four horses are tethered at four corners of a square  plot of side  63 metres so that they  just cannot reach one  another . The area left ungrazed is

A. 675.5`m^2`
B. 780.6 `m^2`
C. 785.8 `m^2`
D. 850.5 `m^2`

2

Four circular cardboard pieces , each of radius 7 cm are placed in such a way  that each piece touches two other piece . The area of the space enclosed by the four piece is

A. 21 `cm^2`
B. 42 `cm^2`
C. 84 `cm^2`
D. 168 `cm^2`

3

If the circumference of a circle increases from ` 4 pi to 8 pi`, what change occurs in its area ?

A. It is halved
B. It doubles
C. It triples
D. It quadruples.

4

If the radius of a circle is doubled its area is increased by :

A. 100 %
B. 200 %
C. 300 %
D. 400 %

5

If the radius of a circle is diminished by 10% , then its area is diminished by  :

A. 10%
B. 19%
C. 20%
D. 36%