Question

1. Periodically, the county Water Department tests the drinking water of homeowners for contminants such as lead and copper. The lead and copper levels in water specimens collected in 1998 for a sample of 10 residents of a subdevelopement of the county are shown below.

lead (μg/L)	copper (mg/L)
0.9	0.268
5.9	0.21
5.7	0.781
3.7	0.835
2.3	0.313
3.3	0.65
3.1	0.52
3.3	0.305
4.5	0.252
2.4	0.397

(a)    Construct a 99% confidence interval for the mean lead level in water specimans of the subdevelopment.
≤μ≤

(b)    Construct a 99% confidence interval for the mean copper level in water specimans of the subdevelopment.  
≤μ≤

2.

The scientific productivity of major world cities was the subject of a recent study. The study determined the number of scientific papers published between 1994 and 1997 by researchers from each of the 20 world cities, and is shown below.

City	Number of papers	City	Number of papers
City 1	21	City 11	22
City 2	24	City 12	24
City 3	28	City 13	27
City 4	19	City 14	21
City 5	4	City 15	16
City 6	25	City 16	24
City 7	20	City 17	16
City 8	10	City 18	19
City 9	20	City 19	14
City 10	14	City 20	26

Construct a 97 % confidence interval for the average number of papers published in major world cities.

<μ<

Answer 1