Done by:

Koh En Song Andrew (Q1211397)

Melissa Teo Kah Leng (E1011088)

Woon Wei Jie Jared

T 04

1.

Over the span of 100 days, the total revenue for Unicafe North and Unicafe West is $21876.60 and $22042.00 respectively. The average revenue for Unicafe North is $218.77. The average revenue for Unicafe West is $220.42. The highest revenue occurred on the 88th day for both outlets. The lowest revenue occurred on 39th day for both outlets. Generally, both outlets earn roughly the same amount of revenue each day.

2a. Confidence interval is a range of values constructed from sample data so that the population parameter is likely to occur within that range at a specific probability (Lind, Marchal & Wathen, 2013).

Using the 95% level of confidence, the confidence interval for Unicafe West is 220.42 6.211. The confidence interval limits are $214.21 and $226.63 (rounded off to 2 decimal places).

Using the 95% level of confidence, the confidence interval for Unicafe North is 218.766 5.571. The confidence interval limits are $213.20 and $224.34 (rounded off to 2 decimal places).

In the event that Mr Yeung wants to predict his potential revenue for the next one hundred days, 95% of the confidence intervals would be expected to contain the population mean. The remaining 5% of the confidence intervals would not contain the population mean, average revenue earned per day. Mr Yeung has correctly estimated that the revenue from both outlets is the same. 2b. Subsequent samples of 100 days may not contain the population mean of this confidence interval as a result of sampling error. Since this confidence interval was obtained from a specific duration of 100 days, it is unlikely that subsequent sample of 100 days would have the exact population mean every time. Sampling errors are random and quite unlikely to occur so it is a reasonable assumption. The sampled population is

References: 1. Lind, D.A., Marchal, W.G. & Wathen, S.A. (2013). Basic Statistics for Business and Economics (8th ed.). New York, NY: McGraw-Hill/Irwin 2. Retrieved Feb 23, 2013, from http://explorable.com/statistics-tutorial