Problem 5. (20 pts) Let r,n N be two natural numbers with r < n. An r x n matrix M consisting of r rows and n columns is said to be a Latin rectangle of size (r, n), if all the entries My belong to the set {1,2,3,..., n), for 1Si<T, 1Sj<T, and the same number does not appear twice in any row or in any column. By defini- tion, a Latin square is a Latin rectangle of size...
Problem 7. (20 pts) Let n N be a natural number and X a finite set with n elements. Show that the number of permutations of X such that no element stays in the same position is n. n! k! For instance, there are 6-3! permutations of 3 elements, but only 2 of them are permutations which fix no element. Similarly, there are 24 41 permutations of 4 elements, but only 9 which fix no element Hint: Use the Inclusion-Erclusion...
Problem 7. (20 pts) Let n EN be a natural nmber and X a finite set with n elements. Show that the number of permutations of X such that no element stays in the same position is n! k! k o For instance, there are 6 = 3! permutations of 3 elements, but only 2 of them are permutations which fix no element. Similarly, there are 24-4! permutations of 4 elements, but only 9 which fix no element. Hint: Use...
Problem 6, (20 pts) How many natural numbers n є N between 1 and 100 are there which are not divisible by 5 nor divisible by 7?
Problem 3. (5 pts) Discrete Random Variables (a) (3 pts) Let A = {1,2,3,4}. Pick a subset B C A uniformly among the 24 subsets (i.e. the power set of A) and let X be its size. Then likewise pick a subset C C B uniformly from the power set of B and let y be its size. Give the joint p.m.f of (X,Y) and compute E(X - Y). Note: X,Y can take value 0 if you pick the empty...
(c) Let N~DU(100), and let X have the value 10, 20, 25, or 50 with probability 1/4 each, independent of N. If N > X, repeatedly subtract X from N until the result is X or smaller. Let Y be the number left over after this repeated subtraction. The number Y is almost the same as the remainder left over after dividing N into X equal parts, ercept that Y will equal X, not 0, if N is evenly divisible...
Problem 3. (5 pts) Discrete Random Variables (a) (3 pts) Let A = {1,2,3,4}. Pick a subset B C A uniformly among the 24 subsets (i.e. the power set of A) and let X be its size. Then likewise pick a subset C CB uniformly from the power set of B and let y be its size. Give the joint p.m.f of (X,Y) and compute E(X – Y). Note: X,Y can take value 0 if you pick the empty set....
4. (20 pts) Let {xn} be a Cauchy sequence. Show that a) (5 pts) {xn} is bounded. Hint: See Lecture 4 notes b) (5 pts) {Jxn} is a Cauchy sequence. Hint: Use the following inequality ||x| - |y|| < |x - y|, for all x, y E R. _ subsequence of {xn} and xn c) (5 pts) If {xnk} is a See Lecture 4 notes. as k - oo, then xn OO as n»oo. Hint: > d) (5 pts) If...
Problem 7. Fix a natural number n € N, and let en denote the equivalence relation "modulo n" on Z defined by x =n y if and only if n|y-r. axun (a) (6 points) Prove that pe N is prime, and if a, b € Z with a? Ep 62, then either a = b or a =p -b. (b) (4 points) Provide a counterexample showing the result in (a) may fail when p is not prime. That is, find...
Prove the Binomial Theorem, that is Exercises 173 (vi) x+y y for all n e N C) Recall that for all 0rS L is divisible by 8 when n is an odd natural number vii))Show that 2 (vin) Prove Leibniz's Theorem for repeated differentiation of a product: If ande are functions of x, then prove that d (uv) d + +Mat0 for all n e N, where u, and d'a d/v and dy da respectively denote (You will need to...