STAT10010 Tutorial 5. Week 7.

October, 2011

1. The following data were collected by a biologist:

Volume of insecticide (ml) 20 19 18 13 10 8 7 6 3 2No of dead insects 36 39 41 45 48 57 58 72 74 76

(a) Decide on a type of plot which could be used to illustrate this data. Givereasons for your choice.

(b) Draw the plot you have selected.

2. Over many years, rainfall totals in Seattle in January range from a low of 0.05inches to a high of 19.5 inches. The median amount of rainfall was 3.1 inches.Based on this information, explain how you can tell that the distribution of rainfallvalues in Seattle in January cannot be bell shaped.

3. Suppose the lengths of time it takes you to commute your daily journey to UCDare bell-shaped with a mean of 20 minutes and a standard deviation of 4 minutes.

(a) Using the empirical rule, what proportion of your journeys to UCD take between16 minutes and 24 minutes?

(b) What is the exact proportion of your journeys that take between 16 and 24minutes?

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