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Two small circular parks of diameters 6 m and 8 m are to be replaced by a bigger circular park. What would be the radius of this new park, in meter, if the new park occupies the same space as the two small parks (in meter)?
5
10
15
20
Answer with explanation
Answer: Option AExplanation
Area of the new circular park = sum of the areas of the 2 smaller parks
⇒ π (6/2)2 + π (8/2)2 = π(9+ 16) = 25π ⇒ 25 π = π R2. ∴ R2 = 25 ⇒ R = 5 m
Workspace
If the length of a certain rectangle is decreased by 4 cm and the width is increased by 3 cm, a square with the same area as the original rectangle would result. Find the perimeter of the original rectangle.
20
30
50
40
Answer with explanation
Answer: Option CExplanation
Let x and y be the length and breadth of the rectangle respectively.
Then, x – 4 = y + 3 or x – y = 7 —-(i)
Area of the rectangle =xy; Area of the square = (x – 4) (y + 3)
(x – 4) (y + 3) =xy <=> 3x – 4y = 12 —-(ii)
Solving (i) and (ii), we get x = 16 and y = 9.
Perimeter of the rectangle = 2 (x + y) = [2 (16 + 9)] cm = 50 cm.
Workspace
The area of a rectangle is 460 square metres. If the length is 15% more than the breadth, what is the breadth of the rectangular field ?
18 meter
20 meter
22 meter
25 meter
Answer with explanation
Answer: Option BExplanation
Area of rectangle = 460 m2
Length = 115% of Breadth
Formula used:
Area of a rectangle = Length × breadth
Calculation:
Let the breadth be x m
Then the breadth will be 1.15x
The area of the rectangle will be
x × 1.5x = 460
⇒ 1.15x2 = 460
⇒ x2 = 460/1.15
⇒ x2 = 400
⇒ x = 20 m
∴ The breadth of the rectangle is 20 m.
Workspace
If the diameters of a circle is increased by 100% . Its area is increased by ?
100%
200%
300%
400%
Answer with explanation
Answer: Option CExplanation
Area of circle = πd2/4
diameters increased by 100%, then new area = π(2d)2 /4 => πd2
Then, New area = (πd2 – πd2/4) => 3πd2/4
increase percent =[(3πd2/4) / ( πd2/4) ]*100 %
= [(3πd2/4) x (4/πd2)]*100 %
= 300%
Workspace
The area of a rectangle is equal to the area of a square whose diagonal is 12√2 metre. The difference between the length and the breadth of the rectangle is 7 metre. What is the perimeter of rectangle ? (in metre).
68 metre
50 metre
62 metre
64 metre
Answer with explanation
Answer: Option BExplanation
d = a√2
12√2 = a√2
a = 12
l * b = a² = (12²) = 144
l – b = 7 ; l = b + 7
(b + 7)*(b) = 144
b² + 7b – 144 = 0
b = 9; l = 16
2(l + b) = 2(16 + 9) = 50m
Workspace
If the length is increased by 25%, by what percent the width of a rectangle should be decreased so as to keep the area same.
25%
10%
20%
30%
Answer with explanation
Answer: Option CExplanation
Let the original length be l and the width be b
Therefore, the area = l*b
Now, as the length is increased by 25%, the new length is (1.25*l) and let the new width be x.
As the area is same, 1.25*l*x = l*b
x = b/1.25 = 0.8b
Therefore, the width is to be decreased by 20%.
Workspace
A man walked 20m to cross a rectangular field diagonally if the length of the field is 16cm then the breadth of the field is
11m
12m
13m
14m
Answer with explanation
Answer: Option BExplanation
Let a rectangular field ABCD
A/Q a man cross rectangular field diagonally and he had to walk 20m
So,Diagonal of Rectangle =20m
Length=16m (given)
We know that Each angle of a rectangle is 90°
ADC forms a right angled triangle
AC=16m(perpendicular)
AD=20m(Hypotenus)
CD=?(base)
According to Pythagorean Theorem
h2=b2+p2
(20)2=b2+(16)2
400=b2+256
b2=144
b=√144
b=12m
Workspace
If the area of the trapezium, whose parallel sides are 6 cm and 10 cm is 32 sq. cm, what will be the distance between the parallel sides?
2 cm
4 cm
5 cm
8 cm
Answer with explanation
Answer: Option BExplanation
Parallel sides of a trapezium = 6 cm, and 10 cm
Area of trapezium =1/2 ( sum of the parallel sides ) × distance between the parallel sides
32=1/2 ( 6+10 ) × distance
32=8 × distance
Distance = 32/8 = 4 cm
So, the distance between the parallel lines of trapezium = 4 cm.
Height = 4 cm
Step-by-step explanation:
Parallel sides = 6 cm and 10 cm
Area of trapezium = 32 cm²
⇒ *(sum of || sides)* h = 32
⇒ * (6 + 10) * h = 32
⇒ 16 / 2 * h = 32
⇒ 8 * h = 32
⇒ h = 32 / 8
⇒ h = 4
Workspace
The ratio of the areas of a square and rhombus whose base is same is:
1:2
2:1
1:1
3:1
Answer with explanation
Answer: Option CExplanation
When parallelogram is on same and located between the same parallels then its area will be equal. It is given rhombus and square are two parallelograms on same base and located between the same parallels.
∴ Area of rhombus = Area of square
∴ Ratio = 1:1
Workspace
The sides of a rectangle are in the ratio 4:3 and its area is 972sq.m find the perimeter of the rectangle?
120m
122m
124m
126m
Answer with explanation
Answer: Option DExplanation
let 4x and 3x be sides of the rectangle
We know that area of rectangle = l×b
4x × 3x = 972
12×2 = 972
X2 = 81
X = 9
Therefore length = 4x = 4×9 = 36m
Breadth = 3x = 3×9 = 27m
Therefore perimeter = 2 (l+b) = 2(36+27) = 126m
Workspace
The ratio between the breadth and perimeter of a rectangle is 2:10. If the area of the rectangle is 428 sq. cm, what is the length of the rectangle?
45.4 cm
25.4 cm
30.4 cm
40.4 cm
Answer with explanation
Answer: Option BExplanation
per the question = 2(L+B)/B = 10/2
2(L+B)/B = 5/1
2L + 2B = 5B
2B – 5B = – 2L
– 3B = – 2L
B = 2/3 L
Given Area = 430 sq. cm.
Area = Length * Breadth
430 = L * 2/3 L
430 = 2/3 L2
Or L2 = 1290 / 2
L2 = 645
L = 25.4 cm
Workspace
How many cubes of 10cm edge can be put in a cubical box of 1m edge
10
100
1000
10000
Answer with explanation
Answer: Option CExplanation
Number of cubes= (100x100x100) / (10x10x10)= 1000
(OR)
The volume of cubical box =100^3 = 1000000cubic cm
Volume of cubes =10^3 =1000cubic cm
Now, no. Of cubes that can be fit in the cubical box = [(The volume of cubical box)/(volume of 1 cube)]
= 1000000/1000
= 1000 cubes
Workspace
The volume of a wall, 5 times as high as it is broad and 8 times as long as it is high, is 12.8 cu. meters. Find the breadth of the wall.
40cm
30cm
20cm
10cm
Answer with explanation
Answer: Option AExplanation
(or)
Given: The volume of a wall is 12.8 m3.
Height is 5 times the breadth and length is 8 times the height.
Let breadth = x
∴ Height = 5x
⇒ Length = 8 × (5x) = 40x
The volume of a Cuboid is given by l × b × h (here l, b, h are, length, breadth, height respectively)
∴ l × b × h = 12.8
⇒ x × 5x × 40x = 12.8
⇒ 200x3 = 12.8
⇒ x3 = 12.8/200 m3 = 8/125
⇒ x= ∛ (8/125)m = 2/5 m = 0.4 m
∴ x = 0.4m = 0.4 × 100 = 40cm
That is Breadth is: 40cm
Workspace
How many bricks each measuring 25cm x 11.25cm x 6cm, will be needed to build a wall 8m x 6m x 22.5m
5600
600
6400
7200
Answer with explanation
Answer: Option CExplanation
No. of bricks= volume of the wall/volume of 1 brick
= (800 x 600 x 22.5) / (25 x 11.25 x 6) = 6400
Workspace
50 men took a dip in a water tank 40 m long and 20 m broad on a religious day. If the average displacement of water by a man is 4 cu.m , then the rise in the water level in the tank will be:
20 cm
25 cm
35 cm
50 cm
Answer with explanation
Answer: Option BExplanation
Workspace
The length, width, and height of a room are 7 m, 8 m, and 9 m respectively. What is the total area of the walls?
270 sq. m.
260 sq. m.
265 sq. m.
255 sq. m.
Answer with explanation
Answer: Option AExplanation
Area of the 4 walls of a room = 2 (Length + Breadth) * Height
Given that, Length = 7 meters, Width or Breadth = 8 meters and Height = 9 meters
So, the required area, A = 2 (7 + 8) * 9
= 2 * 15 * 9
= 270 sq. m.
Workspace
What is the area of the largest circle that can be drawn inside a square of side 20 cm?
90 π cm2
100 π cm2
110 π cm2
95 π cm2
Answer with explanation
Answer: Option BExplanation
The diameter of the largest circle that can be drawn inside a square = length of the side of the square
As per the question: The side of the square = 20 cm.
So, radius of the circle = 20/2 = 10 cm
Area of a circle = π × radius2
The area of the largest circle = π × 102 = 100 π cm2
Workspace
The difference between the length and breadth of a rectangle is 25 meters. If the perimeter of this rectangle is 210 meters, what is its area?
3600 m2
2600 m2
3000 m2
2000 m2
Answer with explanation
Answer: Option BExplanation
The perimeter: 2 (L + B) = 210 or L+ B = 105 …… (i)
As per the question: (L – B) = 25 ……. (ii)
Solving the above two equations:
L + B = 105
B = 105 – L
Put the value of B in (ii).
L – (105 – L) = 25
L – 105 + L = 25
2L = 25 + 105
2L = 130
L = 65
So, – B = 105 – 65 = 40
Now, area of a rectangle: L *B= 65 * 40 = 2600 m2
Workspace
The height of a room to its semi-perimeter is 2: 5. It costs Rs. 260 to paper the walls of the room with paper 50 cm wide at Rs. 2 per meter allowing an area of 15 cm2 for doors and windows. The height of the room is
2.6 m
3.9 m
4 m
4.2 m
Answer with explanation
Answer: Option CExplanation
Workspace
The sides of a rhombus are 10 cm in length, and one diagonal is 16 cm. The area of the rhombus is
96 cm2
95 cm2
94 cm2
93 cm
Answer with explanation
Answer: Option AExplanation
When d1 and d2 are the diagonals of rhombus then,
The Side of rhombus =
Squaring both sides
202 = 162 + d22
400 = 256 + d22
d22 = 400 – 256
d2 = √144
d2 = 12
Area of rhombus =1/2( d1 × d2 )
=1/2 ( 16 × 12 )=96 cm2
Workspace
A rectangular grass field has a length of 85 meters and breadth of 65 meters. It is surrounded by a 5-meter wide path. Find the area of the Path and the cost of constructing it at Rs. 5 per square meter?
4000
6000
8000
7000
Answer with explanation
Answer: Option CExplanation
Area of the entire grass field including the path = Length (85 + 5 +5) * Breadth (65 + 5+5)
= 95 * 75 = 7125 sq. m.
Area of the grass field excluding the path = 85 * 65 = 5525 sq. m.
So, area of the path = 7125 – 5525 = 1600 sq. m.
The cost of constructing is Rs. 5 per square meter.
So, the cost of constructing the entire path = 1600 * 5 = Rs. 8000
Workspace
The perimeter of the rectangular field is 480 meters and the ratio between the length and breadth is 5:3. Find the area of the field.
7200 m2
15000 m2
13500 m2
54000 m2
Answer with explanation
Answer: Option CExplanation
Let the length of the rectangle be 5x, and breadth be 3x,
Perimeter of a rectangle = 2(l +b) = 480
2(5x + 3x) = 480
2 x 8x = 480
16x = 480
x = 480/16 = 30
∴ Length = 5 x 30 = 150 m
Breadth = 3 x 30 = 90 m
And, Area of rectangle = L x B
= 150 x 90 = 13500 m2
Workspace