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Volume and Surface Area

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Friday, March 28, 2025

The area of base of a cylinder is 25 $\pi$ cm $^2$ . If the height of cylinder is 9 cm, then find the total surface area of cylinder.

March 28, 2025 |

General Aptitude, RRB NTPC Exam 27 Jan 2021, Solved, Volume and Surface Area

The area of base of a cylinder is 25 $\pi$ cm $^2$ . If the height of cylinder is 9 cm, then find the total surface area of cylinder.

A

$440 \, \text{cm}^2$

B

$240 \, \text{cm}^2$

C

$420 \, \text{cm}^2$

D

$220 \, \text{cm}^2$

Akhilesh Apr 3 '25 at 19:31

correct answer is: 440 cm²
Explanation: The total surface area of a cylinder is calculated using the formula:

$\text{TSA} = 2\pi r^2 + 2\pi r h$

Given the area of the base $\pi r^2 = 25\pi \, \text{cm}^2$ , we find $r = 5 \, \text{cm}$

With height $h = 9 \, \text{cm}$ , the total surface area is:

$\text{TSA} = 2\pi (5)^2 + 2\pi (5)(9)$

$TSA= 50\pi + 90\pi$

$TSA= 140\pi \, \text{cm}^2$

$TSA = \approx 440 \, \text{cm}^2$

Thus, the correct answer is OPTION a.

OPTION a: Correct, as shown by the calculation.

OPTION b: Incorrect, too low.

OPTION c: Incorrect, too high.

OPTION d: Incorrect, too low.

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Tuesday, January 7, 2020

The area of the base of a rectangular tank is 6500 cm^2 and the volume of water contained in it is 2.6 cubic metres. The depth of the water tank is-

January 07, 2020 |

General Aptitude, RRB ASSISTANT LOCO PILOT (Patna) 2013, Solved, Volume and Surface Area

The area of the base of a rectangular tank is 6500 cm^2 and the volume of water contained in it is 2.6 cubic metres. The depth of the water tank is-

A2.5 metre

B3 metre

C5.5 metre

D4 metre

rahim Jan 8 '2020 at 10:32

Correct answer is: 4 metre

Explanation:

$l \times b = 6500 \text{ cm}^2 = 0.65 \text{ m}^2$
$l \times b \times h = 2.6 \text{ m}^3$
$0.65 \times h = 2.6$
$h =\frac{2.6}{0.65}$
$h = 4m$

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Wednesday, December 26, 2018

What is the volume in cubic cm of a pyramid whose area of

December 26, 2018 |

General Aptitude, RRB TC CC Exam (Mumbai) 2006, Solved, Volume and Surface Area

What is the volume in cubic cm of a pyramid whose area of the base is 25 sq cm and height 9 cm?

A105

B90

C60

D75

Akilesh Kharvi Nov 7 '2016 at 19:14

Answer is : 75

$\text{Volume of pyramid }=\frac{1}{2} \times \text{Area of base} \times \text{height }$

$= \frac{1}{2} \times 25 \times 9$

$= 75 cm^3$

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Friday, November 30, 2018

What part of a ditch, 48 m long 16.5 m broad and 4 m deep can be filled

November 30, 2018 |

General Aptitude, RRB TC CC Exam (Chandigarh) 2008, Solved, Volume and Surface Area

What part of a ditch, 48 m long 16.5 m broad and 4 m deep can be filled by the earth got by digging a cylindrical tunnel of diameter 4 m and length 56 m ?

A

$\frac{1}{9}$

B

$\frac{2}{9}$

C

$\frac{7}{9}$

D

$\frac{8}{9}$

Nithin K Apr 7 '2018 at 16:54

Answer is : b.) $\frac{2}{9}$

Explanation:

Volume of the earth dugout as a tunnel = πr2h

= $\Big(\frac{22}{7}\Big) \times 2 \times 2 \times 56$

= $\text{704 }m^3$
$\text{Volume of the ditch = }\frac{(48 \times 33)}{(2)}\times 4 \implies 24 \times 33 \times 4 \implies \text{3168 }m^3$
∴ $\text{Part required = }\frac{704}{3168} \implies \frac{2}{9}$

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Friday, November 23, 2018

The radius of a right circular cone is 3 cm and its height is 4 cm

November 23, 2018 |

General Aptitude, RRB TA Exam (Malda) 2008, Solved, Volume and Surface Area

The radius of a right circular cone is 3 cm and its height is 4 cm. The curved surface of the cone will be

A

$12 \pi \text{ sq.cm}$

B

$15 \pi \text{ sq.cm }$

C

$18 \pi \text{ sq.cm }$

D

$21 \pi \text{ sq.cm}$

balakrishna Jul 2 '2017 at 11:27

Answer is $15 \pi \text{ sq.cm }$

Explanation:

Slant height of the cone $l = \sqrt{r^2+h^2}$

= $\sqrt{3^2+4^2}$

= $\sqrt{9+16}$

= $\sqrt{25}=5 \text { cm}$

$\therefore$ Area of the curved surface

= $\pi rl$

$=\pi \times3\times5$

$= 15 \pi \text{ sq.cm}$

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