Mensuration(8th Grade > Mathematics ) Questions and answers for exam Preparation

8th Grade > Mathematics

MENSURATION MCQs

Total Questions : 57 | Page 2 of 6 pages

Question 11. If the height of a cylinder is halved and its diameter is doubled then, the new volume is the initial volume.

is equal to
is double of
is three times of
is four times of

Discuss Question

Answer: Option B. -> is double of
:
B
Let the radius of a cylinder be 'r' and the height of a cylinder be 'h'.

Volumeof cylinder = V = π r^{2} h Newradius = 2 r Newheight = \frac{h}{2} New volume = π (2 r)^{2} \frac{h}{2} = 2 π r^{2} h New volume = 2 V

Question 12. PQRS is a quadrilateral in which

P Q = 5 \sqrt{2} c m

Q R = 5 \sqrt{2} c m

R S = 8 c m

S P = 6 c m

∠ P S R = ∠ P Q R = 90^{\circ}

. Then its area is

40.4 cm2
46.4 cm2
32.4 cm2
49 cm2

Discuss Question

Answer: Option D. -> 49 cm2
:
D

PQRS Is A Quadrilateral In Which PQ=5√2cm, QR=5√2cm, RS=...

Area ofright angled triangle

Δ P Q R

= \frac{1}{2} \times B a s e \times H e i g h t = \frac{1}{2} \times 5 \sqrt{2} \times 5 \sqrt{2} = 25 c m^{2}

Area of right angled triangle

Δ P S R

= \frac{1}{2} \times 8 \times 6 = 24 c m^{2}

Area of quadrilateral PQRS
= Area of

Δ P Q R + Δ P S R = 49 c m^{2}

Question 13. An isosceles trapezium has an area of 36 cm², the parallel sides are 12 cm and 6 cm respectively. The perimeter of the trapezium should be

An Isosceles Trapezium Has An Area Of 36 Cm2, The Parallel S...

28 cm
32 cm
24 cm
20 cm

Discuss Question

Answer: Option A. -> 28 cm
:
A

The area of a trapezium is given by:

A = \frac{1}{2} \times (Sum of parallel sides) \times (height)

\Rightarrow 36 = \frac{1}{2} \times (12 + 6) \times h

\Rightarrow h = 4 c m

So now in the trapezium,

h = 4 c m

a = b = 6 c m

A B = C D [S-A-S congruency in △ A F B and △ D E C]

∴ 2 A B + a = 12 c m

\Rightarrow 2 A B = 12 - 6

\Rightarrow A B = C D = 3 c m

So now in △ A B F, A B^{2} + h^{2} = d^{2}

d^{2} = 3^{2} + 4^{2} = 25

d = 5 c m

As the trapezium is isosceles, the slant sides of the trapezium are equal in length

d = c = 5 c m

∴

the perimeter of the trapezium

= (2 \times A B) + a + c + b + d

= (2 \times 3) + 6 + 5 + 6 + 5 = 6 + 22 = 28 c m

Question 14. Every quadrilateral has two pairs of parallel sides.

True
False
24 cm
20 cm

Discuss Question

Answer: Option B. -> False
:
B
A quadrilateral is a four- sided rectilinear figure and parallelogram is a four-sided plane rectilinear figure with opposite sides parallel. Square,rectangle are considered as parallelogram because both of them have opposite sides parallel. In trapezium, only one side is parallel hence, it is not considered as a parallelogram. Hence, every quadrilateral doesn't have two pairs of parallel sides.

Question 15. A cuboid whose length, breadth and height are equal is called a ___________.

Hexagon
Pentagon
Cube
Cuboid

Discuss Question

Answer: Option C. -> Cube
:
C
A cuboid whose length, breadth and height are equal is called a Cube. Cube is a special case of acuboid in which all the sides are equal.

Question 16. A flooring tile has the shape of a rectangle whose dimensions are 10cm × 6cm. How many such tiles are required to cover a floor of area 30 × 50 cm²? (If required you can split the tiles in whatever way you want to fill up the corners).

20 tiles
25 tiles
35 tiles
50 tiles

Discuss Question

Answer: Option B. -> 25 tiles
:
B
Number of tiles required
=

\frac{a r e a o f t h e f l o o r}{a r e a o f o n e t i l e}

\frac{(30 \times 50)}{(10 \times 6)}

= 25 tiles

Question 17. The formula for finding the total surface area of a cuboid is __________.

2×(lb×bh×hl)
2×(lb+bh+hl)
2h×(l+b)
2×lb×(bh+hl)

Discuss Question

Answer: Option B. -> 2×(lb+bh+hl)
:
B
Let l be the length, b be the breadth and h be the height of a cuboid.
The formula for finding thetotal surface area of thecuboid is

2 \times (l b + b h + h l)

Question 18. ___ cm is the height of a cylinder whose radius is 14 cm and the total surface area is 2640 sq.cm

Discuss Question

:
Given, the radius (r) is 14cm.
Let h be the height of the cylinder.
Total surface area of cylinder =2 π r²+ 2 π r h
2640 = 2 x

\frac{22}{7}

x (14)²+ 2 x

\frac{22}{7}

x(14) h .
Hence,h = 16 cm.

Question 19. The area of a trapezium shaped field is 600 m², the distance between two parallel sides is 15 m and one of the parallel side is 20 m. Find the length of the other parallel side.

40 m
50 m
60 m
70 m

Discuss Question

Answer: Option C. -> 60 m
:
C
Let the length of the other parallel side be a.
Given, one of the sides is 20 m and thedistance between two parallel sides is 15 m.
The area of trapezium is given by

= \frac{1}{2} \times

Sum of the length of the two parallel sides

\times

Distance between the two parallel sides.
Hence,
600 =

\frac{1}{2}

(a + 20)× 15
a + 20= 80
a = 80 – 20 = 60
Hence, the length of the other parallel side = 60 m

Question 20. If a square of side 8m and a rectangle of length 12m have the same perimeter, then find the area of the rectangle(in m²)?

36 m2
72 m2
96 m2
48 m2

Discuss Question

Answer: Option D. -> 48 m2
:
D
Let the side of a square be 'a' and length and breadth of a rectangle be 'l' and 'b' respectively.
Given,
Perimeter of square = Perimeter of rectangle
4a = 2(l +b)
4