Water is dripping out from a conial funnel of semi-verticle angle

Subject

Mathematics

Class

ICSE Class 12

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Sample Papers

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 Multiple Choice QuestionsShort Answer Type

21.

A speaks truth in 60% of the cases, while B is 40% of the cases. In what percent of cases are they likely to contradict each other in stating the same fact ?


22.

From a lot of 6 items containing 2 defective items, a sample of 4 items are drawn at random. Let the random variable X denote the number of defective items in the sample. If the sample is drawn without replacement, find :

(a) The probability distribution of X

(b) Mean of X

(c) Variance of X


23.

Find λ if the scalar projection of a = λi^ + j^ + 4k^ on b = 2i^ + 6j^ + 3k^ is 4 units.


24.

The Cartesian equation of line is : 2x - 3 = 3y + 1 = 5 - 6z. Find the vector equation of a line passing through (7, – 5, 0) and parallel to the given line.


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 Multiple Choice QuestionsLong Answer Type

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25.

Water is dripping out from a conial funnel of semi-verticle angle π4 at the uniform rate of 2 cm2/sec in the surface, through a tiny hole at the vertex of the bottom. When the slant height of the water level is 4 cm, find the rate of decrease of the slant height of the water.


Let r be the radius, h be the height and V be the volume of the funnel at any time t.

V = 13πr2h            ...(i)

Let I be the slant height of the funnel

Given, Semi-vertical angle = 45° in the triangle ADE

sin45° = DEAE

 12 = rl

And, cos45° = ADAE

 12 = hl

Thus, r = l2 and h = l2     ...(ii)

Putting these values in equation(i),

V = 13π × l22 × l2

V = π3 × 2 × 2 × I3

V = π62I3              ...(iii)

differentiate w. r. t. t,

dVdt = π62 × 3l2 × dldt

dVdt = π22 × l2 × dldt

dldt = 22πl2 × dldt       ...(iv)

Since it is given that rate of change (decrease) of volume of water w.r.t. t is

dVdt = - 2 cm3/sec

Therefore, dldt = 22πl2 × ( - 2) = - 42πl2

dldtat l = 4 = - 42π42 = - 24π cm/sec

Thus, the rate of decrease of the slant height of the water is - 24π cm/sec.


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26.

Using matrices, solve the following system of equations :

2x - 3y + 5z = 11

3x + 2y - 4z = - 5

x + y - 2z = - 3


27.

Using elementary tranformation, find the inverse of the matrix :

012123311


28.

A cone is inscribed in a sphere of radius 12 cm. If the volume of the cone is maximum, find its height.


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29.

Evaluate: x - 1x2 - xdx


30.

Evaluate: 0π/2cos2x1 + sinxcosxdx


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