Aptitude - Area

6. 

The diagonal of the floor of a rectangular closet is 7 feet. The shorter side of the closet is 4 feet. What is the area of the closet in square feet?

A.
5 1
4
B.
13 1
2
C. 27
D. 37

Answer: Option C

Explanation:

Other side =
15 2 - 9 2
2 2
ft
=
225 - 81
4 4
ft
=
144
4
ft
= 6 ft.

Area of closet = (6 x 4.5) sq. ft = 27 sq. ft.


7. 

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:

A. 10%
B. 10.08%
C. 20%
D. 28%

Answer: Option D

Explanation:

Let original length = x and original breadth = y.

Decrease in area
= xy - 80 x x 90 y
100 100
= xy - 18 xy
25
= 7 xy.
25

Decrease % = 7 xy x 1 x 100 % = 28%.
25 xy


8. 

A man walked diagonally across a square lot. Approximately, what was the percent saved by not walking along the edges?

A. 20
B. 24
C. 30
D. 33

Answer: Option C

Explanation:

Let the side of the square(ABCD) be x metres.

Then, AB + BC = 2x metres.

AC = 2x = (1.41x) m.

Saving on 2x metres = (0.59x) m.

Saving % = 0.59x x 100 % = 30% (approx.)
2x


9. 

The diagonal of a rectangle is 41 cm and its area is 20 sq. cm. The perimeter of the rectangle must be:

A. 9 cm
B. 18 cm
C. 20 cm
D. 41 cm

Answer: Option B

Explanation:

l2 + b2 = 41.

Also, lb = 20.

(l + b)2 = (l2 + b2) + 2lb = 41 + 40 = 81

(l + b) = 9.

Perimeter = 2(l + b) = 18 cm.


10. 

What is the least number of squares tiles required to pave the floor of a room 15 m 17 cm long and 9 m 2 cm broad?

A. 814
B. 820
C. 840
D. 844

Answer: Option A

Explanation:

Length of largest tile = H.C.F. of 1517 cm and 902 cm = 41 cm.

Area of each tile = (41 x 41) cm2.

Required number of tiles = 1517 x 902 = 814.
41 x 41