Volume and Surface Area- Aptitude Questions and Answers - in Hindi

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If cost of painting is Rs 12 per sq meter of surface area, how much will it cost to paint all surfaces of a solid right circular cylinder with height of 9 meters and base area of 154 sq meters?


यदि पेंटिंग की लागत 12 रुपये प्रति वर्ग मीटर सतह क्षेत्रफल है, तो 9 मीटर की ऊंचाई और 154 वर्ग मीटर के आधार क्षेत्रफल के साथ एक ठोस लंब वर्तुल बेलन की सभी सतहों को पेंट करने में कितना खर्च आएगा?

A)

Rs. 8448


B)

Rs. 9372


C)

Rs. 1540


D)

Rs. 3180



Correct Answer :

Rs. 8448


Explanation :

Base area of cylinder = πr2 = 154
r2 = 49
Thus, radius, r = 7

Then, Total Surface Area of cylinder = 2πr(h + r) = 2π*7*(9 + 7)
= 2* 22/7 * 7 *(9 + 7)
= 704

Hence, Cost of painting = 12 * 704
= Rs 8448

If the volume of a cylinder is 2156 cubic cm and height is 14 cm, find its radius?


यदि किसी बेलनाकार वस्तु का आयतन 2156 घन सेमी और ऊँचाई 14 सेमी है, तो इसकी त्रिज्या ज्ञात कीजिए?

A)

14 cm


B)

21 cm


C)

3.5 cm


D)

7 cm



Correct Answer :

7 cm


Explanation :

h = 14 cm, r = ?
Volume = 2156 cm3
πr2h = 2156
22/7 * r2 *14 = 2156
r2 = 2156*7 / 22*14
r2 = 49
r = 7 cm

Find the curved surface area of a right circular cylinder of height 35 cm and the base radius 6 cm?


35 सेमी ऊंचाई और 6 सेमी आधार त्रिज्या के एक लम्ब वृत्तीय बेलन की व्रक पृष्ठीय क्षेत्रफल ज्ञात करे?

A)

1220 cm2


B)

1230 cm2


C)

1320 cm2


D)

1330 cm2



Correct Answer :

1320 cm2


Explanation :

Curved surface area of cylinder= 2πrh
= 2*π*6*35
= 2*(22/7)*6*35 (π = 22/7)
= 1320 cm2

The volume of a cuboid is 3600 m3. If its length is 25 m and its breadth and height are in the ratio 4:1 respectively , then the total surface area of the cuboid is ?


एक घनाभ का आयतन 3600 m3 है। यदि इसकी लंबाई 25 मीटर और इसकी चौड़ाई एवं ऊँचाई क्रमशः 4: 1 के अनुपात में है, तो घनाभ का कुल पृष्ठीय क्षेत्रफल क्या है?

A)

1788 m3


B)

1432 m3


C)

1825 m3


D)

588 m3



Correct Answer :

1788 m3


Explanation :

volume of a cuboid, V = LBH (L=length, B = breadth, H=height).
ratio of breadth and height =3:2, let breadth=4X and height= X.
As given
3600 = 25 * 4X * X
X2 = 36
X = 6
So, breadth=24 height=6

Total Surface Area = 2(LB + BH + HL)
= 2(25*24 + 24*6 + 6*25)
= 12(25*4 + 24 + 25)
= 12(149)
= 1788

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