A spherical balloon is filled with 4500π cubic meters of helium

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

11.

The area bounded between the parabolas x2=y/4 and x2 = 9y, and the straight line y = 2 is

  • 20 square root of 2
  • fraction numerator 10 space square root of 2 over denominator 3 end fraction
  • fraction numerator 20 space square root of 2 over denominator 3 end fraction
  • fraction numerator 20 space square root of 2 over denominator 3 end fraction
721 Views

12.

If the line fraction numerator straight x minus 1 over denominator 2 end fraction space equals space fraction numerator straight y plus 1 over denominator 3 end fraction space equals space fraction numerator straight z minus 1 over denominator 4 end fraction and fraction numerator straight x minus 3 over denominator 1 end fraction space equals fraction numerator straight y minus straight k over denominator 2 end fraction space equals space straight z over 1 intersect, then k is equal to

  • -1

  • 2/9

  • 9/2

  • 9/2

157 Views

13.

Three numbers are chosen at random without replacement from {1, 2, 3, ...... 8}. The probability that their minimum is 3, given that their maximum is 6, is

  • 3/8

  • 1/5

  • 1/4

  • 1/4

206 Views

14.

If z ≠ 1 and fraction numerator straight z squared over denominator straight z minus 1 end fraction is real, then the point represented by the complex number z lies

  • either on the real axis or on a circle passing through the origin

  • on a circle with centre at the origin

  • either on the real axis or on a circle not passing through the origin

  • either on the real axis or on a circle not passing through the origin

159 Views

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15.

The length of the diameter of the circle which touches the x-axis at the point (1, 0) and passes through the point (2, 3) is

  • 10/3

  • 3/5

  • 6/5

  • 6/5

172 Views

16.

Let X = {1, 2, 3, 4, 5}. The number of different ordered pairs (Y, Z) that can be formed such that Y ⊆ X, Z ⊆ X and Y ∩ Z is empty, is

  • 52

  • 35

  • 25

  • 25

248 Views

17.

An ellipse is drawn by taking a diameter of the circle (x–1)2 + y2 = 1 as its semiminor axis and a diameter of the circle x2 + (y – 2)2 = 4 as its semi-major axis. If the centre of the ellipse is the origin and its axes are the coordinate axes, then the equation of the ellipse is

  • 4x2+ y2 = 4

  • x2 +4y2 =8

  • 4x2 +y2 =8

  • 4x2 +y2 =8

398 Views

18.

A line is drawn through the point (1, 2) to meet the coordinate axes at P and Q such that it forms a triangle OPQ, where O is the origin. If the area of the triangle OPQ is least, then the slope of the line PQ is

  • -1/4

  • -4

  • -2

  • -2

268 Views

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19.

A spherical balloon is filled with 4500π cubic meters of helium gas. If a leak in the balloon causes the gas to escape at the rate of 72π cubic meters per minute, then the rate (in meters per minute) at which the radius of the balloon decreases 49 minutes after the leakage began is

  • 9/7

  • 7/9

  • 2/9

  • 2/9


C.

2/9

Volume of balloon is,space straight V space equals space 4 over 3 πr cubed
After 49 minutes volume = 4500π – 49 (72π) = 972π
4 over 3 space πr cubed space equals space 972 space straight pi
rightwards double arrow space straight r cubed space space equals space 729
rightwards double arrow space straight r space equals space 9
Now comma
straight v equals 4 over 3 πr cubed
differentiating space both space the space sides
dv over dt space equals space 4 over 3 space straight pi 3 straight r squared dr over dt
72 space straight pi space equals space 4 πr squared space dr over dt
dr over dt space equals space fraction numerator 72 over denominator 4.9.9 end fraction space equals space 2 over 9

1221 Views

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20.

Let A = open square brackets table row 1 0 0 row 2 1 0 row 3 2 1 end table close square brackets. If u1 and u2 are column matrices such that Au1 = open square brackets table row 1 row 0 row 0 end table close square brackets and Au2 = open square brackets table row 0 row 1 row 0 end table close square brackets, then u1 +u2 is equal to

  • open square brackets table row cell negative 1 end cell row 1 row 0 end table close square brackets
  • open square brackets table row cell negative 1 end cell row cell space space space 1 end cell row cell negative 1 end cell end table close square brackets
  • open square brackets table row cell negative 1 end cell row cell negative 1 end cell row 0 end table close square brackets
  • open square brackets table row cell negative 1 end cell row cell negative 1 end cell row 0 end table close square brackets
480 Views

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