Two model helicopters, the Xtreme and the Firebird, were tested through an obstacle course. Twelve volunteers flew each model through the same obstacle course. The time taken (in seconds) by the models to complete the course was recorded for each volunteer and given below. The order in which the models were flown was randomised for each volunteer.

Volunteer #	1	2	3	4	5	6	7	8	9	10	11	12
Xtreme	29	19	24	25	27	26	21	20	19	27	30	21
Firebird	26	19	20	21	29	27	20	20	19	28	28	30

a) Is the times should be analysed as paired data? Explain. [1 mark]

b)Calculate a 95% confidence interval for the difference Xtreme - Firebird in time for the two helicopter models and interpret the interval. [5 marks]

Mean (round to 3 decimals)