Date | May 2021 | Marks available | 4 | Reference code | 21M.2.AHL.TZ1.5 |
Level | Additional Higher Level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | Hence and Find | Question number | 5 | Adapted from | N/A |
Question
Long term experience shows that if it is sunny on a particular day in Vokram, then the probability that it will be sunny the following day is . If it is not sunny, then the probability that it will be sunny the following day is .
The transition matrix is used to model this information, where .
The matrix can be written as a product of three matrices, , where is a diagonal matrix.
It is sunny today. Find the probability that it will be sunny in three days’ time.
Find the eigenvalues and eigenvectors of .
Write down the matrix .
Write down the matrix .
Hence find the long-term percentage of sunny days in Vokram.
Markscheme
finding OR use of tree diagram (M1)
the probability of sunny in three days’ time is A1
[2 marks]
attempt to find eigenvalues (M1)
Note: Any indication that has been used is sufficient for the (M1).
A1
attempt to find either eigenvector (M1)
so an eigenvector is A1
so an eigenvector is A1
Note: Accept multiples of the stated eigenvectors.
[5 marks]
OR A1
Note: Examiners should be aware that different, correct, matrices may be seen.
[1 mark]
OR A1
Note: and must be consistent with each other.
[1 mark]
(M1)
OR (A1)
Note: Award A1 only if their corresponds to their
(M1)
A1
[4 marks]