Q: An error of 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is

100 cm is read as 102 cm a = 100 x 100 sq.cm and b = 102 x 102 sq.cm then, Increase in area = [ (102 x 102) - (100 x 100) ] sq.cm percentage error = 404 100 * 100 * 100 = 4.04%

Question 1

A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:

Accepted Answer

Let original length = x and original breadth = y. Decrease in area = xy - 80 100 x × 90 100 y = (7/25)xy Decrease % = (7/25)xy * (1/xy) * 100 = 28%

Question 2

A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required?

Accepted Answer

We have: l = 20 ft and lb = 680 sq. ft.So, b = 34 ft. Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.

Question 3

Find the length of the altitude of an equilateral triangle of side 33 cm.

Accepted Answer

Let the length of the altitude be h. Then, h = a 3 2 = 3 3 × 3 2 = 4.5

Question 4

A square and rectangle have equal areas. If their perimeters are p and q respectively. Then

Accepted Answer

square and a rectangle with equal areas will satisfy the relation p < q

Question 5

An error of 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is

Accepted Answer

100 cm is read as 102 cm a = 100 x 100 sq.cm and b = 102 x 102 sq.cm then, Increase in area = [ (102 x 102) - (100 x 100) ] sq.cm percentage error = 404 100 * 100 * 100 = 4.04%

Area Questions