Calcium is essential to tree growth because it promotes the formation of wood and maintains cell walls. In 1990, the concentration of calcium in precipitation in a certain area was

0.11

milligrams per liter (mg/L). A random sample of 10 precipitation dates in 2007 results in the following data table. Complete parts (a) through (c) below.

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Part 1

(a) State the hypotheses for determining if the mean concentration of calcium precipitation has changed since 1990.

H0:

mu

equals=

0.11

mg/L

H1:

mu

not equals

0.11

mg/L

Part 2

(b) Construct a

90%

confidence interval about the sample mean concentration of calcium precipitation.

The lower bound is

. 1076

The upper bound is

. 2062

(Round to four decimal places as needed.)

Part 3

(c) Does the sample evidence suggest that calcium concentrations have changed since 1990?

A. Yes,

because the confidence interval

doesnotcontain

0.11

mg/L.

B. Yes,

because the confidence interval

contains

0.11

mg/L.

C. No,

because the confidence interval

contains

0.11

mg/L.

D. No,

because the confidence interval

doesnotcontain

0.11

mg/L.