RRB NTPC - Problems on Volumes

1.

The height of a cylinder is 60 Cm and the diameter of its base is 5 Cm. The total surface area of the cylinder is : 

   A.) 981 Cm2
   B.) 982.13 Cm2
   C.) 982.14 Cm2
   D.) None of these

Answer: Option 'C'

Given h = 60 Cm and r = 5/2 Cm 
Total surface area = 2πrh + 2&pir2 
= 2πr(h+r) 
= [2 × 22/7 × 5/2 × (60 + 5/2)] Cm2 
= [ 44/7 × 5/2 × ( (120 + 5)/2 ) ] Cm2 
= 22/7 × 5 × 125/2 Cm2 
= (55 × 125)/7 Cm2 
= 6875/7 Cm2 
= 982.14 Cm2

2.

The radius of a cylinder is 10 m, height 14 m. The volume of the cylinder is: 

   A.) 4000 m2
   B.) 4300 m2
   C.) 4000 m3
   D.) None of these

Answer: Option 'C'

Cylinder volume = πr2h
= 22/7 × 10 × 10 × 14 
= 4400 m3

3.

The side of a cube is 8 m, Find the voiume? 

   A.) 513 m3
   B.) 514 m3
   C.) 512 m3
   D.) 502 m3

Answer: Option 'C'

Cube Volume = a3
a3 = 83 = 512 m3

4.

The radius of a cone is 4 m, height 5 m. Find the curved surface area?

   A.) 4 units
   B.) 5 units
   C.) 6 units
   D.) 3 units

Answer: Option 'B'

Cone curved surface area = πrl = 22/7 × 4 × 5 = 440/7 = 62 6/7 
Slant height (l) = √r2+h2 = √16+9 = √25 = 5

5.

Two cylinders of theis radius in the ratio 3 : 5 and heights in the ratio 10 : 9. Then find the volumes ratio? 

   A.) 5 : 2
   B.) 5 : 3
   C.) 2 : 3
   D.) 2 : 5

Answer: Option 'D'

πR2H : πr2
9 × 10 : 25 × 9 
90 : 225 
2 : 5

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