HSC Science (Computer Science) 12th Board ExamMaharashtra State Board
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# Question Paper Solutions - Mathematics and Statistics 2014 - 2015 HSC Science (Computer Science) 12th Board Exam

SubjectMathematics and Statistics
Year2014 - 2015 (October)

Marks: 80
[12]1
[6]1.1 | Select and write the most appropriate answer from the given alternatives in each of the following sub-questions:
[2]1.1.1

If p ˄ q = F, p → q = F, then the truth value of p and q is :

(A) T, T

(B) T, F

(C) F, T

(D) F, F

Chapter: [1] Mathematical Logic
Concept: Mathematical Logic - Truth Value of Statement in Logic
[2]1.1.2

If A^-1=1/3[[1,4,-2],[-2,-5,4],[1,-2,1]] and | A | = 3, then (adj. A) = _______

(A)1/9[[1,4,-2],[-2,-5,4],[1,-2,1]]

(B)[[1,-2,1],[4,-5,-2],[-2,4,1]]

(C)[[1,4,-2],[-2,-5,4],[1,-2,1]]

(D)[[-1,-4,2],[2,5,-4],[1,-2,1]]

Chapter: [2] Matrices
Concept: Determinants - Adjoint Method
[2]1.1.3

The slopes of the lines given by 12x2 + bxy + y2 = 0 differ by 7. Then the value of b is :

(A) 2

(B) ± 2

(C) ± 1

(D) 1

Chapter: [4] Pair of Straight Lines
Concept: Acute Angle Between the Lines
[6]1.2 | Attempt any THREE of the following:
[2]1.2.1

In a Δ ABC, with usual notations prove that: (a -bcos C) /(b -a cos C )= cos B/ cos A

Chapter: [3] Trigonometric Functions
Concept: Trigonometric Functions - Solution of a Triangle
[2]1.2.2

Find ‘k’, if the equation kxy + 10x + 6y + 4 = 0 represents a pair of straight lines.

Chapter: [4] Pair of Straight Lines
Concept: Acute Angle Between the Lines
[2]1.2.3

If A, B, C, D are four non-collinear points in the plane such that bar(AD)+bar( BD)+bar( CD)=bar O then prove that point D is the centroid of the ΔABC.

Chapter: [7] Vectors
Concept: Vectors - Centroid Formula for Vector
[2]1.2.4

Find the direction cosines of the line

(x=2)/2=(2y-5)/3; z=-1

Chapter: [8] Three Dimensional Geometry
Concept: Direction Cosines and Direction Ratios of a Line
[2]1.2.5

Show that the points (1, 1, 1) and (-3, 0, 1) are equidistant from the plane bar r (3bari+4barj-12bark)+13=0

Chapter: [10] Plane
Concept: Distance of a Point from a Plane
[14]2
[6]2.1 | Attempt any TWO of the following:
[3]2.1.1

Using truth table prove that p ↔ q = (p ∧ q) ∨ (~p ∧ ~q).

Chapter: [1] Mathematical Logic
Concept: Mathematical Logic - Truth Tables of Compound Statements
[3]2.1.2

Show that every homogeneous equation of degree two in x and y, i.e., ax2 + 2hxy + by2 = 0 represents a pair of lines passing through origin if h2ab0.

Chapter: [4] Pair of Straight Lines
Concept: Pair of Straight Lines - Pair of Lines Passing Through Origin - Homogenous Equation
[3]2.1.3

Prove that the volume of a parallelopiped with coterminal edges as   bara ,bar b , barc

Hence find the volume of the parallelopiped with coterminal edges  bar i+barj, barj+bark

Chapter: [7] Vectors
Concept: Scalar Triple Product of Vectors
[8]2.2 | Attempt any TWO of the following:
[4]2.2.1

Find the inverse of the matrix,  A=[[1,3,3],[1,4,3],[1,3,4]]by using column transformations.

Chapter: [2] Matrices
Concept: Elementary Operation (Transformation) of a Matrix
[4]2.2.2

In ΔABC, prove that : tan((a-b)/2)=(a-b)/(a+b)cotC/2

Chapter: [3] Trigonometric Functions
Concept: Trigonometric Functions - Solution of a Triangle
[4]2.2.3

Show that the lines  (x+1)/-3=(y-3)/2=(z+2)/1;  are coplanar. Find the equation of the plane containing them.

Chapter: [10] Plane
Concept: Coplanarity of Two Lines
[14]3
[6]3.1 | Attempt any TWO of the following:
[3]3.1.1

Construct the simplified circuit for the following circuit:

Chapter: [1] Mathematical Logic
Concept: Mathematical Logic - Application - Introduction to Switching Circuits
[3]3.1.2

Express -bari-3barj+4bark   as a linear combination of vectors  2bari+barj-4bark,2bari-barj+3bark

Chapter: [7] Vectors
Concept: Vectors - Linear Combination of Vectors
[3]3.1.3

Find the length of the perpendicular from the point (3, 2, 1) to the line (x-7)/2=(y-7)/2=(z-6)/3=lambda (say)

Chapter: [8] Three Dimensional Geometry
Concept: Three - Dimensional Geometry - Condition for Perpendicular Lines
[8]3.2 | Attempt any TWO of the following
[4]3.2.1

Show that the angle between any two diagonals of a cube is cos^-1(1/3)

Chapter: [10] Plane
Concept: Angle Between Line and a Plane
[4]3.2.2

Minimize : Z = 6x + 4y

Subject to the conditions:

3x + 2y ≥ 12,

x + y ≥ 5,

0 ≤ x ≤ 4,

0 ≤ y ≤ 4

Chapter: [11] Linear Programming Problems
Concept: Graphical Method of Solving Linear Programming Problems
[4]3.2.3

If tan^-1((x-1)/(x-2))+cot^-1((x+2)/(x+1))=pi/4;

Chapter: [3] Trigonometric Functions
Concept: Basic Concepts of Trigonometric Functions
[12]4
[6]4.1 | Select and write the most appropriate answer from the given alternatives in each of the following sub-questions
[2]4.1.1

If y=sec^-1((sqrtx-1)/(x+sqrtx))+sin_1((x+sqrtx)/(sqrtx-1)),

(A) x

(B) 1/x

(C) 1

(D) 0

Chapter: [13] Differentiation
Concept: Derivative - Derivative of Inverse Function
[2]4.1.2

If int_(-pi/2)^(pi/2)sin^4x/(sin^4x+cos^4x)dx, then the value of I is:

(A) 0

(B) π

(C) π/2

(D) π/4

Chapter: [15] Integration
Concept: Methods of Integration - Integration by Parts
[2]4.1.3

The solution of the differential equation dy/dx = sec x – y tan x is:

(A) y sec x = tan x + c

(B) y sec x + tan x = c

(C) sec x = y tan x + c

(D) sec x + y tan x = c

Chapter: [17] Differential Equation
Concept: General and Particular Solutions of a Differential Equation
[6]4.2 | Attempt any THREE of the following:
[2]4.2.1

Evaluate: int1/(xlogxlog(logx))dx

Chapter: [15] Integration
Concept: Evaluation of Definite Integrals by Substitution
[2]4.2.2

Find the area bounded by the curve y2 = 4axx-axis and the lines x = 0 and x = a.

Chapter: [16] Applications of Definite Integral
Concept: Area of the Region Bounded by a Curve and a Line
[2]4.2.3

Find k, such that the function  P(x)=k(4/x) ;x=0,1,2,3,4 k>0

=0 ,otherwise

Chapter: [20] Bernoulli Trials and Binomial Distribution
Concept: Standard Deviation of Binomial Distribution (P.M.F.)
[2]4.2.4

Given is X ~ B (n, p). If E(X) = 6, and Var(X) = 4.2, find the value of n.

Chapter: [20] Bernoulli Trials and Binomial Distribution
Concept: Bernoulli Trials and Binomial Distribution - Calculation of Probabilities
[2]4.2.5

Solve the differential equation y-xdy/dx=0

Chapter: [17] Differential Equation
Concept: Methods of Solving First Order, First Degree Differential Equations - Differential Equations with Variables Separable
[14]5
[6]5.1 | Attempt any TWO of the following:
[3]5.1.1

Discuss the continuity of the function

f(x)=(1-sinx)/(pi/2-x)^2,

= 3,                  for x=π/2

Chapter: [12] Continuity
Concept: Continuity - Discontinuity of a Function
[3]5.1.2

If f'(x)=k(cosx-sinx), f'(0)=3 " and " f(pi/2)=15, find f'(x).

Chapter: [14] Applications of Derivative
Concept: Maxima and Minima
[3]5.1.3

Differentiate cos^-1((3cosx-2sinx)/sqrt13) w. r. t. x.

Chapter: [13] Differentiation
Concept: Derivatives of Inverse Trigonometric Functions
[8]5.2 | Attempt any TWO of the following:
[4]5.2.1

Show that:  int1/(x^2sqrt(a^2+x^2))dx=-1/a^2(sqrt(a^2+x^2)/x)+c

Chapter: [15] Integration
Concept: Methods of Integration - Integration by Substitution
[4]5.2.2

A rectangle has area 50 cm2 . Find its dimensions when its perimeter is the least

Chapter: [14] Applications of Derivative
Concept: Maxima and Minima - Introduction of Extrema and Extreme Values
[4]5.2.3

Prove that : int_-a^af(x)dx=2int_0^af(x)dx , if f (x) is an even function.

= 0,                   if f (x) is an odd function.

Chapter: [15] Integration
Concept: Methods of Integration - Integration by Parts
[14]6
[6]6.1 | Attempt any TWO of the following:
[3]6.1.1

If y = f (u) is a differential function of u and u = g(x) is a differential function of x, then prove that y = f [g(x)] is a differential function of x and dy/dx=dy/(du) xx (du)/dx

Chapter: [14] Applications of Derivative
Concept: Rate of Change of Bodies Or Quantities
[3]6.1.2

Each of the total five questions in a multiple choice examination has four choices, only one of which is correct. A student is attempting to guess the answer. The random variable x is the number of questions answered correctly. What is the probability that the student will give atleast one correct answer?

Chapter: [19] Probability Distribution
Concept: Probability Distribution of a Discrete Random Variable
[3]6.1.3

If f (x) = x 2 + a, for x ≥ 0  =2sqrt(x^2+1)+b,  is continuous at x = 0, find a and b.

Chapter: [12] Continuity
Concept: Continuity - Continuity of a Function at a Point
[8]6.2 | Attempt any TWO of the following
[4]6.2.1

Find the approximate value of cos (89°, 30'). [Given is: 1° = 0.0175°C]

Chapter: [14] Applications of Derivative
Concept: Maxima and Minima
[4]6.2.2

Solve the differential equation:  x+ydy/dx=sec(x^2+y^2) Also find the particular solution if x = y = 0.

Chapter: [17] Differential Equation
Concept: General and Particular Solutions of a Differential Equation
[4]6.2.3

Find the expected value, variance and standard deviation of random variable X whose probability mass function (p.m.f.) is given below:

 X=x 1 2 3 P(X=x) 1/5 2/5 2/5
Chapter: [19] Probability Distribution
Concept: Probability Distribution - Expected Value, Variance and Standard Deviation of a Discrete Random Variable
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