Question 1

A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom at 75 paise per sq. m, is:

Accepted Answer

Area to be plastered= [2(l + b) x h] + (l x b) = [2(25 + 12) x 6] + (25 x 12) = (444 + 300) = 744 sq.m Cost of plastering = Rs.744 x (75/100)

Question 2

Two concentric circles form a ring. The inner and outer circumferences of ring are 5187 m and 3527 m respectively. Find the width of the ring.

Accepted Answer

Let the inner and outer radii be r and R metres. Then 2 πR = 352 7 = > R = 352 7 * 7 22 * 1 2 = 8 m 2 πR = 528 7 = > R = 528 7 * 7 22 * 1 2 = 12 m => Width of the ring = (R - r) = (12 - 8) m = 4 m.

Question 3

If the radius of a circle is decreased by 50% , find the percentage decrease in its area.

Accepted Answer

let original radius = r and new radius = (50/100) r = r/2 original area = πr 2 and new area = π r / 2 2 decrease in area = 3 πr 2 / 4 * 1 πr 2 *100 = 75%

Question 4

The length of a rectangle is 12 cm. What is the width if the area is 72 cm ?

Accepted Answer

A=lb

Question 5

Find the perimeter of the rectangle or square with the given dimensions l = 5 feet, w = 2 feet?

Accepted Answer

We know that, Perimeter of rectangle = 2(L+W) = 2(5 + 2) = 2 (7) = 14 fts.

Question 6

Find the perimeter of the rectangle or square with the given dimensions s = 3 cm

Accepted Answer

P=4s

Question 7

In a wheelchair slalom event, athletes weave around cones and race to the finish line. A diagram of the rectangular course is shown. Find the perimeter of the course

Accepted Answer

P = 2l + 2w

Area Questions