a2zinterviews

10.	Spheres A and B have their radil 40 cm and 10 cm respectively. The ratio of the surface area of A to the surface area of B is
	A.  1 : 4
	B.   1 : 16
	C.  4 : 1
	D.  16 : 1

Solution

Let the radil of A and B be r and R respectively. Required ratio = 4Πr2/ 4ΠR2 ‹=› r2 / R2 ‹=› (r/R)2 ‹=›(40/10)2 ‹=› 16 : 1.

11.	How many cubes of 10 cm edge can be put in a cubical box of 1 m edge?
	A.  10
	B.  100
	C.  1000
	D.  10000

Solution

Number of cubes = (100×100×100 /10×10×10) ‹=› 1000.

12.	The cost of the paint is Rs. 36.50 per kg. If 1 kg of paint covers 16 squares feet, how much will it cost to paint outside of a cube having 8 feet each side?
	A.  Rs. 692
	B.  Rs. 768
	C.  Rs. 876
	D.  Rs. 972

Solution

Surface area of the cube = (6 ×82)sq.ft = 384 sq.ft. Quantity of paint required = (384 / 16)kg ‹=›24 kg. Cost of painting = Rs.(36.50 ×24) = Rs. 876.