0.075 0.073 0.052 0.256 0.128 0.171 0.126 0.205 0.322 0.116 Calcium is essential
ID: 3291099 • Letter: 0
Question
0.075
0.073
0.052
0.256
0.128
0.171
0.126
0.205
0.322
0.116
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
0.12
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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(a) State the hypotheses for determining if the mean concentration of calcium precipitation has changed since 1990.
Upper H 0H0:
pp
mu
sigma
not equals
equals=
less than<
greater than>
0.120.12 mg/L
Upper H 1H1:
sigma
pp
mu
equals=
not equals
less than<
greater than>
0.120.12 mg/L(b) Construct a
9090%
confidence interval about the sample mean concentration of calcium precipitation.
(nothing,nothing)
(Use ascending order. Round to four decimal places as needed.)
(c) Does the sample evidence suggest that calcium concentrations have changed since 1990?
A.
NoNo,
because the confidence interval
containscontains
0.120.12
mg/L.
B.
YesYes,
because the confidence interval
does not containdoes not contain
0.120.12
mg/L.
C.
YesYes,
because the confidence interval
containscontains
0.120.12
mg/L.
D.
NoNo,
because the confidence interval
does not containdoes not contain
0.120.12
mg/L.
0.075
0.073
0.052
0.256
0.128
0.171
0.126
0.205
0.322
0.116
Explanation / Answer
from above:
a) H0 equals=0.12
H1 not equals 0.12
b)
for above (10-1=9) degree of freedom and 90%CI; t=1.833
therefore 90% confidence interval =sample mean -/+ t*std error =0.1022 ; 0.2026
c)
No,
because the confidence interval contains 0.12 mg/L.
d)
X 0.075 0.073 0.052 0.256 0.128 0.171 0.126 0.205 0.322 0.116 mean(X) 0.1524 std deviation(S) 0.0867 std error =S/(n)1/2 0.0274Related Questions
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