LOYOLA COLLEGE (AUTONOMOUS), CHENNAI –600 034
B.Sc., DEGREE EXAMINATION – STATISTICS
THIRD SEMESTER – NOVEMBER 2003
ST-3500/STA502 – STATISTICAL MATHEMATICS – II
04.11.2003 Max:100 marks
9.00 – 12.00
SECTION-A
Answer ALL the questions. (10×2=20 marks)
- If P* is a partition of [a , b] finer than the partition P, state the inequality governing the upper sums lower sums of a function f corresponding to P and P*.
- Find .
- State the first Fundamental Theorem of Integral calculus.
- Solve: .
- “The function f(x,y) = xy/(x2+y2) , (x,y) ¹(0,0)
0 , (x, y) = (0, 0)
does not have double limit as (x, y) – verify.
- State the rule for the partial derivative of a composite function of two variables.
- Define Gamma distribution.
- Write down the Beta integral with integrand involving Sine and Cosine functions.
- Define a symmetric matrix.
- Find the rank of the matrix .
SECTION-B
Answer any FIVE questions. (5×8=40 marks)
- Evaluate (a) . (4+4)
(b)
- If f(x) = kx2 , 0 < x¸< 2 , is the probability density function (p.d.f) of X, find (i) k
(ii) P[X<1/4], (iii) P, (iv) P[X >1].
- Solve the non-homogeneous differential equation:
(y – x – 3) dy = (2x + y +6) dx
- For the function xy(x2 – y2) / (x2 + y2) , (x,y) ¹(0,0)
f(x,y) =
0 , (x, y) = (0, 0)
Show that fx (x, 0) = fy (0,y) = 0 , fx (0, y) = -y , fy (x, 0) = x.
- Find the mean and variance of Beta distribution of II kind stating the conditions for their existence.
- If f(x,y) = e-x-y , x > 0, y > 0, is the joint p.d.f of (x, y), find the joint c.d.f. of (x, y). Verify that the second order mixed derivative of the joint c.d.f.is indeed the joint p.d.f.
- Establish the reversal law for Transpose of product of matrices. Show that the operations of Inversion and Transpositions are commutative.
- Find the inverse of using Cayley – Hamilton Theorem.
SECTION-C
Answer any TWO questions. (2×20=40 marks)
- a) Show that, if fÎ R [a, b] then f2 Î R [ a, b].
- b) If f(x) = c.e-x, x > 0, is the p.d.f. of X, find (i) c (ii) E(X), (iii) Var (X).
- c) Discuss the convergence of (8+6+6)
- a) Investigate for extreme values of the function
f (x, y) = x3 + y3 – 12x – 3y + 5, x, y Î R.
- b) Define joint distribution function for bivariate case and state its properties. Establish
the property which gives the probability P[x1 < X £ x2, y1 < Y £ y2] in terms of the
joint distribution function of (X, Y). (10+10)
- If x + y , 0 < x, y < 1
f (x, y) =
0 , otherwise
is the joint p.d.f of (x, y), find the means and variances of X and Y and covariance
between X and Y. Also find P [ Y < X] and the marginal p.d.f’s of X and Y.
- a) By partitioning into 2 x 2 submatrices find the inverse of
- b) Find the characteristic roots and any characteristic vectors for the matrix
(10 + 10)