Question

1.the volume of earth must be dug out to make a well of diameter 5m and depth 14m is?

2. the lateral surface area and the total surface area of a cylinder with base radius 7m and height 9m are ?

3. the length of a rectangle is 1cm more than it's width and it's perimeter is 14 . then the area of the rectangle is ?

4. If each the dimension of a rectangle is increased by 100%. then the area is increased by?


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Answer 1

Answer:

1 volumes of cylinder =

$\pi {r}^{2} h$

Diameter =5

Radius =2.5

Height =14

Volume =275m3

2.Given s= 7m, h=9 m

Lateral surface area = Area of the curved surface =2πrh=2× 22/7 ×7m×9m=396m 2

Total surface area = Area of curved surface + Area of two circular surfaces

=2πrh+2πr ^2 =396m^2+2×22/7×7m×7m=(396+308)m ^2

=704m 2

3.Let the width of the rectangle is x cm

Then length of the rectangle =x+1 cm (given length of rectangle is 1 cm more then width

So perimeter of rectangle =2(length+width)=2(x+1+x)=2(2x+1)

But perimeter = 14 cm (Given)

∴2(2x+1)=14

⇒2x+1=7

⇒2x=7−1

⇒x=3

Then wigth =3 cm and length=3+1=4 cm

∴areaofrectangle=length×wigth=4×3=12cm ^2

4.Thus when width and length increased by 100% the area of it increases by 4 times that is 400%

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Answer 2

Answer:

1 volumes of cylinder =

Diameter =5

Radius =2.5

Height =14

Volume =275m3

2.Given s= 7m, h=9 m

Lateral surface area = Area of the curved surface =2πrh=2× 22/7 ×7m×9m=396m 2

Total surface area = Area of curved surface + Area of two circular surfaces

=2πrh+2πr ^2 =396m^2+2×22/7×7m×7m=(396+308)m ^2

=704m 2

3.Let the width of the rectangle is x cm

Then length of the rectangle =x+1 cm (given length of rectangle is 1 cm more then width

So perimeter of rectangle =2(length+width)=2(x+1+x)=2(2x+1)

But perimeter = 14 cm (Given)

∴2(2x+1)=14

⇒2x+1=7

⇒2x=7−1

⇒x=3

Then wigth =3 cm and length=3+1=4 cm

∴areaofrectangle=length×wigth=4×3=12cm ^2

4.Thus when width and length increased by 100% the area of it increases by 4 times that is 400%