Four persons are chosen at random from a group of 3 men, 2 women

Subject

Mathematics

Class

JEE Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

π6π3dx1 + tanx is equal to

  • π12

  • π2

  • π6

  • π4


22.

If f is a continuous function, then

  • - 22f(x)dx = 02f(x) - f(- x)dx

  • - 352f(x)dx = - 610fx - 1dx

  • - 35fxdx = - 44fx - 1dx

  • - 35fxdx = - 26fx - 1dx


23.

An integrating factor of the differential equation

xdydx +ylogx = xexx12logx, (x > 0), is

  • xlogx

  • xlogx

  • elogx2

  • ex2


24.

Solution of the differential equation

dydxtany = sinx + y + sinx - y

  • secy + 2cosx = c

  • secy - 2cosx = c

  • cosy - 2sinx = c

  • tany - 2secy = c


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25.

Four persons are chosen at random from a group of 3 men, 2 women and 4 children. The chance that exactly 2 of them are children, is 

  • 1021

  • 1113

  • 1325

  • 2132


A.

1021

Let S = Number of ways of choosing 4 persons out of 9

= C49 = 9 × 8 × 7 × 64 × 3 × 2 × 1 = 126

and E = Number of ways of choosing 2 children out of 4 and 2 persons out of (3 + 2) persons

= C24 × C25 = 4 × 32 × 1 × 5 × 42 × 1 = 60 Require probability = 60126 = 1021


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