A ball of lead 4 cm in diameter is covered with gold. If the vol

Subject

Quantitative Aptitude

Class

SSCCGL Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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11.

A ball of lead 4 cm in diameter is covered with gold. If the volume of the gold and lead are equal, then the thickness of gold [given cube root of 2 space equals space 1.259] is approximately.

  • 5.038 m

  • 5.190 cm

  • 1.038 cm

  • 1.038 cm


D.

1.038 cm

Diameter of lead = 4 cm
Radius of lead = 2 cm
Volume of lead = 4 over 3 πr cubed space space equals space 4 over 3 straight pi cross times 2 cubed
Let the thickness of gold be x cm, then
        Volume of gold = 4 over 3 straight pi open parentheses left parenthesis 2 plus straight x right parenthesis cubed minus 2 cubed close parentheses space cu. space cm
      therefore space space 4 over 3 straight pi open parentheses open parentheses 2 plus straight x close parentheses cubed minus 2 cubed close parentheses space equals space 4 over 3 straight pi space cross times space 2 cubed
         rightwards double arrow space space left parenthesis 2 plus straight x right parenthesis cubed space minus space 2 cubed space equals space 2 cubed
rightwards double arrow space space left parenthesis 2 plus straight x right parenthesis cubed space space equals space 8 space plus space 8 space equals space 16
rightwards double arrow space space left parenthesis 2 plus straight x right parenthesis cubed space equals space 2 cubed. space 2
          rightwards double arrow space space 2 space plus space straight x space equals space 2 space cross times space cube root of 2
rightwards double arrow space space 2 space space plus space straight x space equals space 2 space cross times space 1.259 space equals space 2.518
therefore space space space space straight x space equals space 2.518 space minus space 2 space equals space 0.518 space cm
  

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12.

A large solid sphere is melted and moulded to form identical right circular cones with base radius and height same as the radius of the sphere. One of these cones is melted and moulded to form a smaller solid sphere. Then the ratio of the surface area of the smaller to the surface area of the larger sphere is

  • 1 space colon space 3 to the power of 4 over 3 end exponent
  • 1 space colon space 2 to the power of 3 over 2 end exponent
  • 1 space colon space 3 to the power of 2 over 3 end exponent
  • 1 space colon space 3 to the power of 2 over 3 end exponent
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13.

Two sides of a plot measuring 32 m and 24 m and the angle between them is a perfect right angle. The other two sides measure 25 m each and the other three angles are not right angles. The area of the plot in m2 is

  • 768

  • 534

  • 696.5

  • 696.5

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14.

a and b are two sides of adjacent to the right angle of a right-angled and p is the perpendicular drawn to the hypotenuse from the opposite vertex. Then p2 is equal to

  • straight a squared plus straight b squared
  • 1 over straight a squared plus 1 over straight b squared
  • fraction numerator straight a squared straight b squared over denominator straight a squared plus straight b squared end fraction
  • fraction numerator straight a squared straight b squared over denominator straight a squared plus straight b squared end fraction
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15.

A conical cup is filled with ice cream. The ice-cream forms a hemispherical shape on its open top. The height of the hemispherical part is 7 cm. The radius of the hemispherical part equals the height of the cone. Then the volume of the ice-cream is open square brackets straight pi space equals space 22 over 7 close square brackets

  • 1078 cubic cm

  • 1708 cubic cm

  • 7108 cubic cm

  • 7108 cubic cm

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16.

A is the centre of a circle whose radius is 8 and B is the centre of a circle whose diameter is 8. If these two two circles touch externally, then the area of the circle with diameter AB is

  • 36 straight pi
  • 64 straight pi
  • 144 straight pi
  • 144 straight pi
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17.

If straight a squared plus straight b squared plus straight c squared space equals space ab space plus bc plus space ac then the value of fraction numerator straight a plus straight c over denominator straight b end fraction is

  • 0

  • 2

  • 1

  • 1

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18.

If ab + bc + ca = 0, then the value of open parentheses fraction numerator 1 over denominator straight a squared minus bc end fraction space plus space fraction numerator 1 over denominator straight b squared minus ca end fraction plus fraction numerator 1 over denominator straight c squared minus ab end fraction close parentheses is

  • 0

  • 1

  • 3

  • 3

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19.

If left parenthesis 2 plus square root of 3 right parenthesis straight a space equals space left parenthesis 2 minus square root of 3 right parenthesis straight b space equals space 1 then the value of 1 over straight a plus 1 over straight b is

  • 1

  • 2

  • 2 square root of 3
  • 2 square root of 3
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20.

If 3 straight x plus 3 over straight x space equals space 1, then straight x cubed plus 1 over straight x cubed plus 1 is

  • 0

  • 1 over 27
  • 5 over 27
  • 5 over 27
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