a. Calculate the four-quarter centred moving averages for the following time series. (6 marks)

Quarter	2018	2019	2020	2021
1	62	48	50	43
2	51	45	46	39
3	53	44	46	37
4	46	37	42	32

b. Monthly sales (in $1000s) of a US company are shown below.

Month	Jan	Feb	Mar	Apr
Sales	73	65	72	82

Compute the exponentially smoothed sales over the four months, with w = 0.3 and w = 0.5. (4 marks)

Note: You are required to submit your workings and calculations to the space below for this question.