MATH 1004 Mathematics For Data Science I Semester 2, 2022
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Sample Examination, Semester 2, 2022
MATH 1004 Mathematics For Data Science I
MATH 1004UAC Mathematics For Data Science I - UAC
/2 marks 1(a) Given A = {1, 4, α, H}, B = {4, u, 2, −2}, C = {u}, determine each of
(i) (A n B) ∩ C
(ii) A / B
/2 marks 1(b) Let f(x) = ,
Evaluate the following:
(i) f(g(0))
(ii) g(g(1/2))
/2 marks 1(c) Consider the function h(x) = x2 for x ∈ [ − 1, ∞). Explain why this
/2 marks 1(d) Evaluate
51
i≠2
showing working.
/2 marks
(i) How many binary sequences are there of length 8?
(ii) How many binary sequences of length 8 contain exactly 5 ones?
2(b) Consider the following table of probabilities for the three possible
outcomes of an experiment X:
x |
1 |
2 |
3 |
P (X = x) |
0.1 |
0.6 |
a |
(i) What must a be for X to be a valid discrete random variable? (ii) What is the expectation value of X?
(iii) What is the variance of X?
2(c) A city consists of two electoral divisions: A and B. The population of
division A is 107,000, and the population of division B is 105,000. At an election the probabilities of voting for the Centre Party given that a voter was in division A was 0.16, and the probability of voting for the Centre Party given that they were in division B was 0.07.
(i) What is the probability that a randomly chosen voter is from division A?
(ii) What is the probability that a randomly chosen voter voted for
the Centre Party? Use the law of total probability to find the probability of selecting a Centre Party voter at random from the city.
(iii) What is the probability that a voter is from division A given that
they voted for the Centre Party?
a 0 1 2 3
(i) If this function represents a probability density function then determine the value of a.
(ii) What is the probability that X is greater than 2?
3(b) Consider the pdf for a continuous probability distribution:
g(北) = (1 − 北2 )
(0
Given that the expectation value of this distribution is , determine
the variance.
3(c) Let f (北) = 北5/2 .
(i) Calculate the third-degree Taylor polynomial for the function f (北) about the centre a = 1.
(ii) Use your Taylor polynomial to find an approximation for 25/2 .
X = ┌ 6 2┐ , Y = '(┌)5 1'(┐)
If possible, calculate the following. If not possible, give a reason for your answer.
(i) X + YT
(ii) YX
(iii) the determinant |X|
4(b) Suppose that B is a 5 ×3 matrix and A-1 BT C is invertible. Determine
the sizes of A and C, giving reasoning.
4(c) Suppose that Alice buys packets of nuts and dried fruit for a party.
Each packet of nuts costs $5 and a packet of dried fruit costs $6.
In total she spends $72, and she buys 1 more packet of dried fruit than the number of packets of nuts that she buys.
Formulate a system of linear equations which could be used to deter- mine the number of each type of snack that Alice buys, and solve the system.
/2 marks
reduced row echelon form
┌0(1) 4(0)┐
Find the set of solutions to this system of equations.
5(b) Consider the system of equations
x + 2y + 2z = 1
2x + y − 2z = 0
2x − 2y + z = 1
(i) Write down the matrix A and vector b such that the above system of equations can be written in matrix form Ax = b.
(ii) After reducing the augmented system [A|I] to row-echelon form,
we obtain ┌0(1) ' |
2 1 0 |
2 2 1 |
1 0 6/9 −3/9 2/9 −2/9 |
0(0) ┐ 1/9' |
By performing further row operations, find the inverse matrix A-1 . Make sure you state all row operations you are using.
(iii) Hence find the solution x to the equation in part (i).
5(c) Explain why the set {u, v, 0} is linearly dependent for vectors u, v ∈ Rn and 0 ∈ Rn .
/5 marks 6(a) Consider the matrix
A = ┌ 1 5(4)┐ .
(i) Find the eigenvalues of A
(ii) Find the eigenvectors for each eigenvalue?
(iii) Is A diagonalisable? Give a reason for your answer.
6(b) Suppose that a matrix B satisfies B ┌ ┐1(1) = ┌ ┐1(1) and B ┌ ┐0(1) = ┌ 1┐ .
Give a matrix P which diagonalises B and the corresponding diagonal matrix.
6(c) Suppose that a matrix C is diagonalised by
P = ┌ 1(1) 2(1)┐ with D = ┌0(d) 0(0)┐ .
Given that P-1 = ┌ 1(2) 1(1)┐ , find C5 in terms of d.
2022-11-12