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Maths | CBSE Board | Grade 12 | 2015
Q. In a factory which manufactures bolts, machines A, B and C manufacture 30%, 50% and 20% of the bolts respectively. Of their output 3%, 4% and 1% respectively are defective bolts. A bolt is drawn at random from the product and is found to be defective. Find the probability that this is not manufactured by machine B.
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Q. Evaluate: (32x).2+xx2dx.
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Q. The equation of a line is 5x3=15y+7=310z. Write the direction cosines of the line.
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Q. Find λ, if the vectors a=^i+3^j+^k, b=2^i^j^k and c=λ^j+3^k are coplanar.
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Q. If y=emsin1x, then show that (1x2)d2ydx2xdydxm2y=0.
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Q. Find (π/40dxcos3x2sin2x).
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Q. Using integration, prove that the curves y2=4x and x2=4y divide the area of the square bounded by x=0, x=4, y=0 and y=4 into three equal parts.
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Q. Solve for x:
tan1(x+1)+tan1(x1)=tan1831
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Q. If a=^i+2^j+^k, b=2^i+^j and c=3^i4^j5^k, then find a unit vector perpendicular to both of the vectors (ab) and (cb).
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Q. To promote the making of toilets for women, an organization tried to generate awarencess through:
(i) house calls
(ii) letters
(iii) announcements.
The cost for each mode per attempt is given below:
(i) Rs 50
(i) Rs 20
(i) Rs 40
The number of attempts made in three villages X, Y and Z are given below:
(i)(ii)(iii)
X400300100
Y30025075
Z500400150
Find the total cost incurred by the organization for the three villages separately, using matrices.
Write one value generated by the organization in the society.
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Q. Write the element a23 of a 3×3 matrix A(aij) whose elements are represented by aij=|ij|2.
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Q. Find the adjoint of the matrix A=122212221 and
hence show that
A.(adjA)=|A|I3.
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Q. Find the equation of a line passing through the point (1, 2, 4) and perpendicular to two lines r=(8^i19^j+10^k)+λ(3^i16^j+7^k) and r=(15^i+29^j+5^k)+μ(3^i+8^j5^k).
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Q. Show that the function f(x)=|x1|+|x+1|, for all xR, is not differentiable at the points x=1 and x=1.
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Q. Three cards are drawn successively with replacement from a well shuffled pack of 52 cards. Find the probability distribution of the number of spades. Hence find the mean of the distribution.
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Q. Using properties of determinants, prove the following:
∣ ∣ ∣a2bcac+c2a2+abb2acabb2+bcc2∣ ∣ ∣=4a2b2c2.
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Q. A company manufactures three kinds of calculators : A, B and C in its two factories I and II, The company has got an order for manufacturing at least 6400 calculators of kind A, 4000 of kind B and 4800 of kind C. The daily output of factory I is of 50 calculators of kind A, 50 calculators of kind B, and 30 calculators of kind C. The daily output of factory II is of 40 calculators of kind A, 20 of kind B and 40 of kind C. The cost per day to run factory I is Rs. 12, 000 and of factory II is Rs. 15, 000.
How many days do the two factories have to be in operation to produce the order with the minimum cost? Formulate this problem as an LPP and solve it graphically.
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Q. Write the sum of the order and degree of the following differential equation: ddx{(dydx)3}=0.
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Q. If f(x)=x2+1, g(x)=x+1x2+1 and h(x)=2x3, then find f[h|g(x)|].
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Q. Write a unit vector perpendicular to both the vectors a=^i+^j+^k and b=^i+^j.
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Q. Find (logx(x+1)2dx).
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Q. Write the value of =∣ ∣x+yy+zz+xzxy333∣ ∣.
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Q. Find the distance of the point P(3, 4, 4) from the point, where the line joining the point A(3, 4, 5) and B(2, 3, 1) intersects the plane 2x+y+z=7.
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Q. Show that the differential equation dydx=y2xyx2 is homogeneous and also solve it.
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Q. If A=2^i+7^j+3^k and B=3^i+2^j+5^k, then find the projection of a on b.
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Q. Find the value of p for which the curves x2=9p(9y) and x2=p(y+1) cut each other at right angles.
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Q. Write the integrating factor of the following differential equation:
(1+y2)+(2xycoty)dydx=0.
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Q. If ^a, ^b and ^c are mutually perpendicular unit vectors, then find the value of |2^a+^b+^c|.
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Q. Consider f:R+[9, ] given by f(x)=5x2+6x9. Prove that f is invertible with f(y)=(54+5y35).
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Q. If a line makes angles 90o, 600 and θ with x, y and z axis respectively, where θ is acute, then find θ.
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