All questions of Mensuration for Civil Engineering (CE) Exam

A circular wire of radius 56 cm is cut and bent in the form of a rectangle whose sides are in the ratio of 6:5. The smaller side of the rectangle is
  • a)
    70cm
  • b)
    75cm
  • c)
    80cm
  • d)
    85cm
  • e)
    None of these
Correct answer is option 'C'. Can you explain this answer?

Preeti Khanna answered
The perimeter of the circle, that is, the rectangle is,
P=2πr = 2 * 22/7 * 56 =16×22 cm.
Let us assume the actual length and breadth of the rectangle be, 6xand 5x
So perimeter will be,
P=2(6x+5x)=22x
16×22=22x
X=16.
The smaller side or breadth =5x=80cm

Circumference of a circle A is 22/7 times perimeter of a square. Area of the square is 441 cm². What is the area of another circle B whose diameter is half the radius of the circle A(in cm²)?
  • a)
    354.5
  • b)
    346.5
  • c)
    316.5
  • d)
    312.5
  • e)
    None of the Above
Correct answer is option 'B'. Can you explain this answer?

Anshul Singh answered
Area of square=441 cm2
i.e. (side)2=441 cm2
side=21cm

Circumference of circle A=2πr
Perimeter of square(p)=4*side=(4*21)cm=84cm

According to question,
Circumference of A=22/7 of p
i.e. 2πr=(22/7)*84
2(22/7)*r=(22/7)*84
2r=84
r=42cm

let radius of B be 'R',
Diameter of B=(1/2) of radius of A
Diameter of B=(1/2)*42=21cm
R=(21/2)cm

Area of Circle B=πR2
=(22/7)*(21/2)*(21/2)cm2
hence on calculating the above solution we
get that area of circle B=346.5
i.e. option b).
thanking you if you understand it so plzzz follow me.

If each side pair of opposite sides of a square is increased by 20 m, the ratio of the length and breadth of the rectangular so formed becomes 5:3. The area of the old square is?
  • a)
    990m²
  • b)
    900m²
  • c)
    930m²
  • d)
    945m²
  • e)
    None of the Above
Correct answer is option 'B'. Can you explain this answer?

Ankur Mathur answered
Let the side of squares be x sq unit.
therefore as a pair opposite side increased by 20 units, hence now the rectangle obtained is of dimension-:
x, (x+20)

also the ration of sides is 5:3
so,
(x+20/x)= 5/3

solving this you will get X=30

hence the dimension of the square was of 30*30
hence area was 900sq unit.

A solid metallic cylinder of base radius 5 cm and height 7 cm is melted to form cones, each of height 1 cm and base radius 1 mm. Find the number of cones?
  • a)
    53500
  • b)
    49500
  • c)
    51500
  • d)
    52500
  • e)
    None of these
Correct answer is option 'D'. Can you explain this answer?

Aarav Sharma answered
To solve this problem, we need to find the number of cones that can be formed by melting a solid metallic cylinder.

Given:
Base radius of the cylinder = 5 cm
Height of the cylinder = 7 cm
Height of each cone = 1 cm
Base radius of each cone = 1 mm = 0.1 cm

We can start by finding the volume of the cylinder and the volume of each cone.

1. Volume of the cylinder:
The volume of a cylinder can be calculated using the formula V = πr^2h, where r is the base radius and h is the height. In this case, the radius of the cylinder is 5 cm and the height is 7 cm.
So the volume of the cylinder is V_cylinder = π(5^2)(7) = 175π cm^3.

2. Volume of each cone:
The volume of a cone can be calculated using the formula V = (1/3)πr^2h, where r is the base radius and h is the height. In this case, the radius of each cone is 0.1 cm and the height is 1 cm.
So the volume of each cone is V_cone = (1/3)π(0.1^2)(1) = (1/300)π cm^3.

Next, we need to find the number of cones that can be formed by dividing the volume of the cylinder by the volume of each cone.

3. Number of cones:
Number of cones = V_cylinder / V_cone
Number of cones = (175π) / ((1/300)π) = 52500

Therefore, the number of cones that can be formed is 52500.

Hence, the correct answer is option D) 52500.

The length of a rectangular plot is 10 metres more than its breadth. If the cost of fencing the plot @ 26.50 per metre is Rs. 5300, what is the length of the plot in metres?
  • a)
    50
  • b)
    55
  • c)
    60
  • d)
    65
  • e)
    None of the Above
Correct answer is option 'B'. Can you explain this answer?

Aarav Sharma answered
Given:
- Length of the rectangular plot = breadth + 10
- Cost of fencing the plot = Rs. 5300
- Cost per meter of fencing = Rs. 26.50

To find:
Length of the plot in meters

Solution:

Let's assume the breadth of the rectangular plot to be 'x' meters.

According to the given information, the length of the rectangular plot is 10 meters more than its breadth.
So, the length of the plot = x + 10 meters.

Perimeter of the rectangular plot:
The perimeter of a rectangle is given by the formula:
Perimeter = 2(length + breadth)

In this case, the perimeter of the plot is equal to the cost of fencing.
So, 2(length + breadth) = Rs. 5300

Substituting the values of length and breadth, we get:
2(x + 10 + x) = 5300

Simplifying the equation:
2(2x + 10) = 5300
4x + 20 = 5300
4x = 5300 - 20
4x = 5280
x = 5280/4
x = 1320/1
x = 1320 meters

So, the breadth of the rectangular plot is 1320 meters.

Now, we can find the length of the plot:
Length = breadth + 10
Length = 1320 + 10
Length = 1330 meters

Therefore, the length of the plot is 1330 meters.

Answer:
The length of the plot is 55 meters. (Option B)

The length of a plot is four times its breath. A playground measuring 400 square meters occupies one fourth of the total area of a plot. What is the length of the plot in meter.?
  • a)
    20
  • b)
    30
  • c)
    60
  • d)
    40
  • e)
    80
Correct answer is option 'E'. Can you explain this answer?

Aarav Sharma answered
To solve this problem, we need to use the given information to find the length of the plot. Let's break down the information step by step:

1. The length of a plot is four times its breadth: Let's assume the breadth of the plot is 'x'. According to the given information, the length of the plot would be 4x.

2. A playground occupies one fourth of the total area of the plot: The area of the playground is given as 400 square meters. Since the playground occupies one fourth of the total area of the plot, we can calculate the total area of the plot by multiplying the area of the playground by 4. So, the total area of the plot would be 400 * 4 = 1600 square meters.

3. Now, we can use the total area of the plot to find the length. The formula to calculate the area of a rectangle is length * breadth. We know that the area of the plot is 1600 square meters and the length is 4x. Substituting these values into the formula, we get:

4x * x = 1600

4. Simplifying the equation, we have:

4x^2 = 1600

5. Dividing both sides of the equation by 4, we get:

x^2 = 400

6. Taking the square root of both sides, we get:

x = √400

7. Simplifying the square root, we have:

x = 20

8. Since the length of the plot is four times its breadth, we have:

Length = 4x = 4 * 20 = 80 meters

Therefore, the length of the plot is 80 meters. The correct answer is option E.

The length of a park is four times of its breadth. A playground whose area is 1600 m² covers 1/4th part of the park. The length of the park is?
  • a)
    108 m
  • b)
    140 m
  • c)
    120 m
  • d)
    160 m
  • e)
    180 m
Correct answer is option 'D'. Can you explain this answer?

Sagar Sharma answered
The area of a rectangle is given by the formula A = length * breadth.

Let's assume the breadth of the park is x meters.
According to the problem, the length of the park is four times its breadth, so the length is 4x meters.

The area of the park is given as 1600 square meters, so we can write the equation:
1600 = 4x * x

Simplifying the equation:
1600 = 4x^2

Dividing both sides by 4:
400 = x^2

Taking the square root of both sides:
x = ±20

Since the breadth cannot be negative, we take the positive value:
x = 20 meters

Therefore, the breadth of the park is 20 meters and the length is 4 times the breadth, which is 4*20 = 80 meters.

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