What are the answers to the Associate Exam Practice Questions?

I got c,b,c,b,a but I would like a confirmed answer. See: http://www.mathworks.com/services/training/certification/exam-questions.html

[Helen Kirby]

I got a,b,c,a,d

[Rik]

Comment posted as answer by Keith Meyers:

Why does A for the first question work? It doesn't make any logical sense and it shouldn't work. Can someone explain where they found that way to get the corners?

[Guillaume]

Why doesn't it make any logical sense? What code do you use to get the inner 2x2 matrix of a 4x6 matrix:

M(2:3, 3:4)
%which is the same as
M([2 3], [3 4])

which basically returns the intersection of rows 2 and 3 with columns 3 and 4. With the same logic,

M([1, end], [1, end])

is the intersection of 1st and last row with 1st and last column, hence the 4 corners.

Answer 1

[Decky]

I got C D C A D.

[Guillaume]

Try harder! The correct answers are A, D, C, A, D. C for the first question is going to result in an error. You can't use a cell array to index a matrix.

[Ahmed Hassan]

Indeed, the correct answers are: A, D, C, A, D

Answer 2

[David Verrelli]

The questions are more difficult than they might appear. After testing in MATLAB I could confirm the correct answers, and I recommend this practical approach to others. (And if you then don't understand why, then read the documentation on each command.) By my count the first Dan got 1/5, and the second Dan got 3/5.... —DIV

Answer 3

[Daniel Chappell]

C - four corners, so four elements indexed B - number of positive elements divided by the total number of elements C - index with end, and set this element to blank A - x-axis appears as first argument (plot(time, acceleration) D - std(Z) is a column-wise (default) statistical function

[Helen Kirby]

Re: the first one: Sounds logical, but actually doesn't work if you try that command out. The answer is A