The concentration of carbon dioxide (CO_2) in the atmosphere is increasing rapid

Question

The concentration of carbon dioxide (CO_2) in the atmosphere is increasing rapidly due to our use of fossil fuels. Because plants use CO_2 to fuel photosynthesis more CO_2 may cause and other plants to grow faster. An trees elaborate apparatus allows researchers to Pipe extra CO_2 to a 30-meter circle of forest. They selected two nearby circles in each of three parts of a plane forest and randomly chose one of each pair to extra CO_2. The response variable is the mean increase in base area for 30 to 40 trees in a circle during a growing season. We measure this in percent increase per year. Here are one year's data. (a) State the null alternatives hypothesis. (Where mu is the mean difference, control.) mu_0: mu_0: Explain clearly why used a one-sided alternatives. The researchers have reason to believe that CO_2 will increase growth rate. The researchers have no preconceived idea what extra CO_2 will do to the growth rate. The researchers have reason to believe that CO_2 decrease growth rate, (b) Carry out a test and report your conclusion in simple language. (Use alpha = 0.05. Use 2 decimal places). t = Conclusion: There is evidence of a increase in growth rates due to extra CO_2. There is no evidence of a increase in growth rates due to extra CO_2.

Explanation / Answer

H0: µ = 0

Ha:µ > 0

Pair

Control plot

Treated plot

D2-d2

1

9.728

10.668

0.94

2

7.124

8.096

0.972

3

5.636

6.668

1.032

Mean

7.496

8.4773

0.9813

= 0.9813

Sd = = 0.0467

SE = sd / sqrt( n ) = 0.02965

Degree of freedom = n-1 =2

t = Where D is the hypothesized mean difference, here D = 0

t = 0.9813/0.02965 = 33.096

From T- distribution table with t = 33.096 and df = 2

We have P = 0.000456

Pair

Control plot

Treated plot

D2-d2

1

9.728

10.668

0.94

2

7.124

8.096

0.972

3

5.636

6.668

1.032

Mean

7.496

8.4773

0.9813

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