Geometry and Mensuration

Total Questions: 54

11. LMNOP is a semicircle with centre at R and diameter LP. LSR and RQP are also semi circles with centres at T and U respectively and diameters LR = RP = (1/2) LP. [1998]

The ratio of perimeter of LMNOP and LSRQP is

Correct Answer: (b) 1 : 1
Solution:Let

Perimeter of

Perimeter of Perimeter of Perimeter of

Perimeter

12. A square pond has 2 m sides and is 1 m deep. If it is to be enlarged, the depth remaining the same, into a circular pond with the diagonal of the square as diameter as shown in the figure, then what would be the volume of earth to be removed? [1998]

Correct Answer: (a) (2π – 4) m³ 
Solution:Diagonal of the square

Radius of the circle

Volume to be removed ( Volume of the square - Volume of the circle )

13. The surface area of spherical dome-shaped roof of a cylindrical water tank shown in the figure is [1999]

Correct Answer: (b) 109 πm²
Solution:Let Radius of the sphere = rm

OX = OY = 10 m

d = 2r - 3 ∴ x × y = c × d

10 × 10 = 3(2r - 3) 6r - 9 = 100, 6r = 109

r = m

14. A hemispherical bowl is filled to the brim with a beverage. The contents of the bowl are transferred into a cylindrical vessel whose radius is 50% more than its height. If the diameter is same for both bowl and cylinder, then the volume of the beverage in the cylindrical vessel will be [1999]

Correct Answer: (c) 100%
Solution:

Let the radius of hemispherical bowl = r
∴ Volume of hemispherical bowl = (2/3)πr³

Let the height of cylindrical vessel = h
r = h(1 + 50/100) = (2/3)r

Volume of cylindrical vessel = πr²(2r/3) = (2/3)πr³

Hence, volume of the beverage in the cylindrical vessel = (2/3)πr³ / (2/3)πr³ × 100% = 100%

15. A man is standing on the 6m long pole whose length of shadow is 8m. If the length of his shadow is 2.4m, what is the height of the man? [1999]

Correct Answer: (c) 1.8 m
Solution:

In △ABD and △EBC,

BD/AB = BC/BE = 10.4/6x = 6/8

x = 1.8 m.
Where, x = height of the man.

16. If the angle of triangle are in the ratio of 4 : 3 : 2, then the triangle [1999]

Correct Answer: (d) is acute angled triangle
Solution:Let the angles be 4x, 3x and 2x. 4x + 3x + 2x = ; x =

angles are , and .

17. At a given time, two players are standing on a play-field. The cartesian coordinates of their locations are (20, 60) and (–40, –20) units. What is the distance between the players? [1999]

Correct Answer: (c) 100 units
Solution:

18. The area of an ellipse is twice that of a circle. The major diameter of the ellipse is twice that of the minor diameter. The radius of the circle is [1999]

Correct Answer: (a) 50% of minor diameter of the ellipse
Solution:Let the minor diameter of ellipse = 2b

Major diameter of ellipse = 2a = 2(2b)

2a = 4b a = 2b

Let the radius of circle = r

Now, ab =

or (2b)b =

∴ r = b

Radius of circle = 1/2 minor diameter of ellipse

= 50% of minor diameter of an ellipse

19. In the given figure ∠OQP = 30° and ∠ORP = 20°, then ∠QOR is equal to [2000]

 

Correct Answer: (b) 120°
Solution:

20. Which one of the following has a greater perimeter than the rest? [2000]

Correct Answer: (c) A rectangle with 10 cm as length and 40 sq cm as area
Solution:

( a ) Side of the square = √36 = 6 cm

Perimeter of the square = 4 ( 6 ) = 24 cm

( b ) Perimeter of the triangle = 9 + 9 + 9 = 27 cm

( c ) Area of the rectangle = 40

lb = 40

b = 40/10 = 4

Perimeter = 2 ( l + b ) = 2 ( 4 + 10 ) = 28 cm

( d ) Perimeter of the circle = 2πr = 2 ( 3.14 ) ( 4 ) = 25.12 cm
Clearly , Perimeter of the rectangle is maximum .