Question Paper: Engineering Mathematics 4 : Question Paper Dec 2012 - Electronics & Communication (Semester 4) | Visveswaraya Technological University (VTU)
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Engineering Mathematics 4 - Dec 2012

Electronics & Communication (Semester 4)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.
1 (a) Using the Taylor's series method, solve the initial value problem $$\dfrac {dy}{dx}=x^2 y-1, y(0)=1$$ at the point x=0.1(6 marks) 1 (b) Employ the fourth order Runge-Kutta method to solve $$\dfrac {dy}{dx}= \dfrac {y^2-x^2}{y^2+x^2} y(0)=1$$ at the points x=0.2 and x=0.4. Take h=0.2.(7 marks) 1 (c) $$Given \ \dfrac {dy}{dx}= xy+y^2, \ y(0)=1, \ y(0.1)=1.1169, \ y(0.2)=1.2773, \ y(0.3)=1.5049$$ Find y(0.4) using the Milne's predictor-corrector method, Apply the corrector formula twice.(7 marks) 2 (a) Exmploying the Picard's method, obtain the second order approximate solution of the following problem at x=0.2. $$\dfrac {dy}{dx}=x+yz, \ \dfrac {dz}{dx}= y+zx, \ y(0)=1, \ z(0)=-1$$(6 marks) 2 (b) Using the Runge-kutta method, find the solution at x=0.1 of the differential equation $$\dfrac {d^2y}{dx^3}- x^2 \dfrac {dy}{dx}- 2xy =1$$ under the conditions y(0)=1, y'(0)=0. Take step length h=0.1.(7 marks) 2 (c) Using the Milne's method, obtain an approximate solution at the point x=0.4 of the problem $$\dfrac {d^2y}{dx^2}+3x \dfrac {dy}{dx}-6y=0, \ y(0)=1, \ y'(0)=0.1$$ Given y(0.1)=1.03995, y'(0.1)=0.6955, y(0.2)=1.138036, y'(0.2)=1.258, y(0.3)=1.29865, y'(0.3)=1.873.(7 marks) 3 (a) If f(z)=u+iv is an analytic function then prove that $$\left [ \dfrac {\partial }{\partial x} |f(z)| \right ]^2 + \left [ \dfrac {\partial }{\partial y} |f(z)| \right ]^2 =|f'(z)|^2$$(6 marks) 3 (b) Find an analytic function whose imaginary part is v=ex{(x2-y2) cos y-2xy sin y}(7 marks) 3 (c) If f(z)=u(r,?)+ iv(r,?) is an analytic function, show that u and v satisfy the equation $$\dfrac {\partial^2 \varphi}{\partial r^2}+ \dfrac {1}{r} \dfrac {\partial \varphi}{ \partial r}+ \dfrac {1}{r^2} \dfrac {\partial^2 \varphi}{\partial \theta^2}=0$$(7 marks) 4 (a) Find the bilinear transformation that maps the points 1, i, -1 onto the point i, 0, -i respectively.(6 marks) 4 (b) Discuss the transformation W=ex.(7 marks) 4 (c) Evaluate $$\int_C \dfrac {\sin \pi z^2 + \cos \pi z^3}{(z-1)^2 (z-2)}dz$$ where C is the circle |z|=3.(7 marks) 5 (a) Express the polynomial 2x3-x2-3x+2 in terms of Legendre polynomials.(6 marks) 5 (b) Obtain the series solution of Bessel's differential equation $$x^2 \dfrac {d^2 y}{dx^2}+ x \dfrac {dy}{dx}+ (x^2-n^2)y=0$$ in the form y=AJn(x) + BJ-n(x).(7 marks) 5 (c) Derive Rodrique's formula $$P_n(x)= \dfrac {1}{2^n n!} \dfrac {d^n}{dx^n}(x^2-1)^n.$$(7 marks) 6 (a) State the axioms of probability. For any two events A and B, Prove that P(A?B)=P(A)+P(B)-P(A?B).(6 marks) 6 (b) A bag contains 10 white balls and 3 red ball while another bag contains 3 white balls and 5 red balls. Two balls are drawn at random from the first bag and put in the second bag and then a ball is drawn at random from the second bag. What is the probability that it is a white ball?(7 marks) 6 (c) In a bolt factory there are four machines A, B, C, D manufacturing respectively 20%, 15%, 25%, 40% of the total production. Out of these 5%, 4%, 3% and 2% respectively are defective. A bolt is drawn at random from the production and is found to be defective. Find the probability that it was manufactured by A or D.(7 marks) 7 (a) The probability distribution of finite random variable x is given by the following table:

 xi -2 -1 0 1 2 3 p(xi) 0.1 k 0.2 2k 0.3 k

Determine the value of k and find the mean, variance and standard deviation.(6 marks) 7 (b) The probability that a pen manufactured by a company will be defective is 0.1. If 12 such pens are selected, find the probability that (i) exactly 2 will be defective. (ii) at least 2 will be defective, (iii) none will be defective.(7 marks) 7 (c) In a normal distribution, 31% of the items are under 45 and 8% are over 64. Find the mean and standard deviation, given that A(0.5)=0.19 and A(1.4)=0.42, where A(z) is the area under the standard normal curve from O to z>0.(7 marks) 8 (a) A biased coin is tossed 500 times and head turns up 120 times. Find the 95% confidence limits for the propertion of heads turning up in infinitely many tosses. (Given that zc=1.96)(6 marks) 8 (b) A certain stimulus administered to each of 12 patients resulted in the following changes in blood pressure;
5, 2, 8, -1, 3, 0, 6, -2, 1, 5, 0, 4 (in appropriate unit)
Can it be conclude that, on the whole, the stimulus will change the blood pressure. Use t0.05(11)=2.201.
(7 marks)
8 (c) A die is thrown 60 times and the frequency distribution for the number appearing on the face x is given by the following table:

Test the hypothesis that the die is unbiased. (Given that x20.05(5)=11.07 and x20.01(5)=15.09)
(7 marks)