Question

Sample ID	Control	Fertilizer Treatment
1	0.358	0.336
2	0.338	0.438
3	0.488	0.458
4	0.374	0.797
5	0.411	0.588
6	0.442	0.326
7	0.376	0.193
8	0.334	0.297
9	0.498	0.486
10	0.403	0.203
11	0.473	0.5
12	0.238	0.214
13	0.298	0.599
14	0.222	0.2
15	0.318	0.598
16	0.337	0.454
17	0.398	0.563
18	0.35	0.692
19	0.285	0.685
20	0.383	0.493
21	0.275	0.361
22	0.332	0.206
23	0.469	0.701
24	0.497	0.255
25	0.352	0.541
26	0.296	0.49
27	0.48	0.257
28	0.266	0.526
29	0.461	0.822
30	0.26	0.63

A soil scientist has just developed a new type of fertilizer and she wants to determine whether it helps carrots grow larger. She sets up several pots of soil and plants one carrot seed in each pot. Fertilizer is added to half the pots. All the pots are placed in a temperature-controlled greenhouse where they receive adequate light and equal amounts of water. After two months of growth, the scientist harvests the carrots and weighs them (in kilograms). Below is a data table showing the weight of the carrots at the end of the growing period from the two treatment groups. Here is a hyperlink to the data.

When analyzing this dataset with a t-test, the [X] hypothesis states that the average size of the carrots from each treatment are the same, whereas the [X] hypothesis states that the fertilized carrots are larger in size.

To analyze this data set, the scientist should use a [X]-tailed t-test.

1. After performing a t-test assuming equal variances using the data analysis add-in for MS Excel, what is the calculated t-value for this data set?

• Round your answer to 4 decimal places.
• Report your answer as the absolute value of your calculated t statistic.

2. Report the appropriate critical t value, based on your decision of a one- or two-tailed test, calculated by MS Excel using the Data Analysis add-in.

• Round your answer to 4 decimal places.

3. What is the appropriate p value for the t-test?

• Report your answer in exponential notation
• Report your answer to 4 decimal places after converting to exponential notation
• e.g.
  • 1.1234E-01 for 0.112341
  • 3.1234E-04 for 0.000312341

4. Would you reject or fail to reject the null hypothesis?

Answer 1