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The dimensions of an open box are 50 cm, 40 cm and 23 cm. Its thickness is 2 cm. If 1 cubic cm of metal used in the box weighs 0.5 gms, find the weight of the box.
8.04kg
8.14kg
8.24kg
9.04kg
Answer with explanation
Answer: Option AExplanation
Given,
Outer dimensions of the box = 50 cm, 40 cm and 23 cm
Outer volume of the box = 50 × 40 × 23 = 46000 cu cm
Inner dimensions of the box:
Length = (50 – 2×3) = 44 cm
Breadth = (40 – 2×3) = 34 cm
Height = (23 – 30 = 20 cm
Inner volume of the box = 44 × 34 × 20 = 29920 cu cm
Volume of the wood = Outer Volume – Inner Volume = 46000 – 29920 =
16080 cu cm
Weight of the wood per cu cm = 0.5 g
Weight of the wood used for making the box = 16080 × 0.5 = 8040 g = 8.04 kg.
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
Let the breadth of the wall be x metres.
Then, Height = 5x metres and Length = 40x metres.
x * 5x * 40x = 12.8
=> x^3 = 12.8/200
=> x= 0.4m = 40cm
Workspace
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 5C% more than its height. If the diameter is same for bot
25%
50%
75%
100%
Answer with explanation
Answer: Option DExplanation
Since V2 > V1, so the vessel can contain 100% of the beverage filled in the bow
Workspace
A hollow sphere of internal and external diameters 4 cm and 8 cm respectively is melted into a cone of base diameter 8 cm. The height of the cone is :
11 cm
12 cm
13 cm
14 cm
Answer with explanation
Answer: Option DExplanation
Given : Internal diameter of hollow sphere(d)= 4 cm.
Internal radius of hollow sphere (r) = 4/2= 2 cm
external diameter of hollow sphere (D) = 8 cm.
external radius of hollow sphere( R )= 8/2= 4 cm.
Volume of the Hollow sphere = 4/3π(R³ – r³)
Volume of the Hollow sphere = 4/3π(4³ – 2³)
Volume of the Hollow sphere = 4/3π(64 – 8)
Volume of the Hollow sphere = 4/3π(56) cm³
Diameter of the cone(d1) = 8 cm
radius of the cone( r1)= 8/2 = 4 cm
Let the height of the cone be h cm.
Volume of the cone = ⅓ πr1²h
= ⅓ π × 4² × h = 16πh/3
Volume of the cone = Volume of the hollow sphere
16πh/3 = 4/3π(56)
16h = 4 ×56
h = (4 × 56)/16
h = 56/4 = 14 cm
Hence, the height of the cone is 14 cm.
Workspace
A cylindrical vessel of radius 4 cm contains water. A solid sphere of radius 3 cm is lowered into the water until it is completely immersed. The water level in the vessel will rise by
3/4 cm
9/4 cm
11/4 cm
13/4 cm
Answer with explanation
Answer: Option BExplanation
Increase in volume of cylinder = volume of sphere
Let increase in volume of cylinder be = πr2h, where r is its radius and h is its height.
So, 16πh = 4/3 π33
h = 4/3 × 27/16
= 36/16
= 9/4 = 2.25 cm
Workspace
A solid piece of iron of dimensions 49 × 33 × 24 cm is moulded into a sphere. The radius of the sphere is :
21 cm
22 cm
23 cm
24 cm
Answer with explanation
Answer: Option AExplanation
As per the question volume of cuboid=volume of sphere
volume of cuboid=lbh cubic cm
=38808cm3
volume of sphere =4/3pi r cube
4/3 pi r cube=38808cubic cm
r cube =38808×21/4×22
r=21 cm
Workspace
Spheres A and B have their radii 40 cm and 10 cm respectively. The ratio of the surface area of A to the surface area of B is :
10 : 1
12 : 1
14 : 1
16 : 1
Answer with explanation
Answer: Option DExplanation
surface area of sphere = 4× pi × r^2
ratio = surface area of a sphere /surface area of the sphere
= 4 × 3.14 × 40 × 40 / 4 × 3.14 × 10× 10
= 40 × 40 / 10× 10
= 4 × 4 / 1 × 1
= 16 / 1
Ratio = 16 : 1
Workspace
If the volume of a sphere is divided by its surface area, the result is 27 cm. The radius of the sphere is
64 cm
72 cm
81 cm
94 cm
Answer with explanation
Answer: Option CExplanation
Volume of sphere / surface are of sphere = 27 cm
4/3πr^3 / 4πr^2 = 27
r/3 = 27
r = 81 cm
Workspace
The radii of two cones are in the ratio 2 : 1, their volumes are equal. Find the ratio of their height
1 : 1
1 : 2
1 : 3
1 : 4
Answer with explanation
Answer: Option DExplanation
Volume of cone =1/3πr^2h
={(1/3πr^2h)/(1/3πr^2H)}
={(1/3π(2x)^2h)/(1/3π xH)}
=h/H=1/4
so h:H=1:4
Workspace
The slant height of a conical mountain is 2.5 km and the area of its base is 1.54 km². The height of the mountain is :
2.4 km
3.6 km
4.3 km
5.8 km
Answer with explanation
Answer: Option AExplanation
Area of circle= pi r2=1.54
r=0.7
ht. of mountain= sqrt( 2.5×2.5 – .7×.7)=2.4
Workspace
a right triangle with sides 3cm,4cm,5cm is rotated about the side of 3cm to formed a cone. what is the volume of cone?
10
11
37.68
13
Answer with explanation
Answer: Option CExplanation
In Right ∆,
Hypotenuse=5cm,
Base of ∆= Radius of Cone=3cm
3rd side of ∆=Height of Cone=4cm
So,Volume of Cone=1/3πr²h=1/3×3.14×(3)²×4=37.68
Workspace
The number of coins of radius 0.75 cm and thickness 0.2 cm to be melted to make a right circular cylinder of height 8 cm and base radius 3 cm is :
412
560
640
780
Answer with explanation
Answer: Option CExplanation
Coin, r=0.75cm h=0.2cm V=pi r^2h =22/7*0.75*0.75*0.2 =2.475/7cm^3
Cylinder, h=8 cm r=3cm V= 22/7*3*3*8 =1584/7 cm^3 No. of coins=1584/7*7/2.475 =640
Workspace
A cylinder tank of diameter 35 cm is full of water. If 11 litres of water is drawn off, the water level in the tank will drop by:
11.42
12 3/7 cm
13 3/7 cm
14 3/7 cm
Answer with explanation
Answer: Option AExplanation
Let height change = x cm
volume of water dropped = π × (35/2)^2 × x = 11000 cm3
x = 11000
———–π× (17.5) ^2
= 11.42 cm
Workspace
The capacity of a cylindrical tank is 246.4 litres. If the height is 4 metres, what is the diameter of the base
18 m
28 m
38 m
48 m
Answer with explanation
Answer: Option BExplanation
Volume of the tank = 246.4 litres = 246400 cm^3
Let the radius of the base be r cm . Then ,
(22/7 xx r^2 xx 400) = 246400
hArr r^2 = ((246400 xx 7)/(22 xx 400))
hArr r^2 = 196 hArr r = 14
:. Diameer of the base = 2r = 28 cm.
Workspace
An iron cube of side 10 cm is hammered into a rectangular sheet of thickness 0.5 cm. If the sides of the sheet are in the ratio 1 : 5, the sides are :
20 cm, 100 cm
40 cm, 200 cm
60 cm, 300 cm
80 cm, 400 cm
Answer with explanation
Answer: Option AExplanation
Workspace
The cost of the paint is Rs. 36.50 per kg. If 1 kg of paint covers 16 square feet, how much will it cost to paint outside of a cube having 8 feet each side
Rs. 579
Rs. 673
Rs. 774
Rs. 876
Answer with explanation
Answer: Option DExplanation
Given :
Cost of paint = ₹ 36.50/ kg
1 kg paint covers 16 ft^2.
Solution :
Side of the cubic wall = 8 ft
So, total outside surface area of the cube wall
= 6 (side)^2
= 6 × 64 sq. ft
= 384 sq. ft
Amount of paint required
= (384/16) kg
So, total cost = ₹ (384/16) × 36.50
= ₹ 24 × 36.50
= ₹ 876.00
Read more on Brainly.in – https://brainly.in/question/7056608#readmore
Workspace
If the areas of the three adjacent faces of a cuboidal box are 120 cm², 72 cm² and 60 cm² respectively, then find the volume of the box.
560 cm³
640 cm³
720 cm³
880 cm³
Answer with explanation
Answer: Option CExplanation
Area of 3 faces = lb + bh + lh
so, 120 = lb
72 = bh
60 = lh
multiply all three
l²b²h² = 518400
so, lbh =√518400 = 720 cm³
Workspace
A rectangular water tank is 80 m × 40 m. Water flows into it through a pipe 40 sq. cm at the opening at a speed of 10 km/hr. By how much, the water level will rise in the tank in half an hour
1/2 cm
3/5 cm
5/8 cm
9/2 cm
Answer with explanation
Answer: Option CExplanation
Let the water, h mtr. will rise in the tank
l×b×h=Area×speed×time
80×40×h=40/100×100×10000×1/2
h=11/60m=100/160cm=5/8cm
Workspace
The height of a wall is six times its width and the length of the wall is seven times its height. If volume of the wall be 16128 cu. m, its width is:
2
4
6
8
Answer with explanation
Answer: Option BExplanation
he height of the wall is 6 times its width and lenght of the wall is 7 times its height .if the volume of the wall be 16128 cu.m.its width is
A) 4mB) 5mC) 6mD) 7m
Answer: A) 4m
Explanation:
Let width = x
Then, height = 6x and length = 42x
42x * 6x * x = 16128
x = 4
Workspace
The length of the floor if a rectangle hall is 10 m more than its breadth. If 34 carpets of size 6 × 4m are required to cover the floor of the hall, then find the length and breadth of the hall.
24, 24m
24, 34m
22, 32m
34, 34m
Answer with explanation
Answer: Option BExplanation
Let breadth = b then length = b + 10m.
Floor area of the rectangle hall = A = length × breadth = b × (b + 10)
Also area of each carpet = 6 × 4m and 34 pieces are required to cover the floor
Therefore area of hall = 34 × 6 × 4
b × (b + 10) = 34 × 24
Therefore b = 24 m and length = b + 10 = 34m.
Workspace
The side of the cube which can be hold 8 litres of water is
10 cm
15 cm
20 cm
25 cm
Answer with explanation
Answer: Option DExplanation
1 litre = 1000 centimeter cube.
So, 8 litre = 8000 centimeter cube
Side = cuberoot (8000 centimeter cube) = 20 cms.
Workspace