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

lead (g/L) copper (mg/L)

4.3 0.35

5.9 0.472

1.5 0.742

1 0.111

4.9 0.637

5.5 0.369

2.8 0.311

0.4 0.481

0.5 0.601

2 0.607

(a)

Construct a99% confidence interval for the mean lead level in water specimans of the sub-development.

____________

(b)

Construct a99% confidence interval for the mean copper level in water specimans of the subdevelopment.

____________

2)The following random sample was selected from a normal distribution:

10 14 12 17 2 4 12 1 12 11

(a)

Construct a90% confidence interval for the population mean.

__________

(b)

Construct a95% confidence interval for the population mean.

__________