Question

1. Nutrient loss in food products is an important issue for food processing companies. We

would like to determine whether or not bread loses its vitamin C content over time.

a. Go to the Excel spreadsheet “Vitamin C in bread” that is posted with this assignment and

download it. There you will find results of an experiment conducted by a baking company.

The data show vitamin C content of 20 loaves of bread. Five of the loaves had vitamin C

measured the day of baking (day 0). Another five had vitamin C measured one day after

baking (day 1), and so forth for days 3 and 5.

b. Click Tools > Data Analysis and select the appropriate procedure for doing an analysis of

variance. I want to see a printout of the results obtained by using the Data Analysis Tool.

c. Interpret the results. Are there differences among the days in terms of vitamin C content?

What in the output tells you this?

Days after baking
0 days	1 day	3 days	5 days
46.2	37.5	23.1	10.0
54.3	27.0	13.9	13.5
42.9	44.1	24.3	15.8
37.0	31.0	29.4	8.9
38.1	36.7	34.1	25.3

2. Go the Excel spreadsheet “Trends in Vitamin C in bread” that is posted with this

assignment. There you will find the same data as in problem 1 but in a format that will allow

you to get a scatterplot and trendline.

a. Obtain the scatterplot and trendline (include the equation). I want to see a printout of this

analysis.

b. Use the equation in 2a to predict vitamin C content when day = 2. Include the answer on

your spreadsheet.

days	vitamin C
0	46.2
0	54.3
0	42.9
0	37.0
0	38.1
1	37.5
1	27.0
1	44.1
1	31.0
1	36.7
3	23.1
3	13.9
3	24.3
3	29.4
3	34.1
5	10.0
5	13.5
5	15.8
5	8.9
5	25.3

Answer 1

1. b) Go to Data tab --> Data Analysis --> Anova Single Factor. Select the data. Upon doing the above step following is the result:

Anova: Single Factor
SUMMARY
Groups	Count	Sum	Average	Variance
0 D	5	218.5	43.7	48.875
1 D	5	176.3	35.26	42.903
3 D	5	124.8	24.96	57.368
5 D	5	73.5	14.7	42.685
ANOVA
Source of Variation	SS	df	MS	F	P-value	F crit
Between Groups	2371.866	3	790.6218	16.4858	3.76349E-05	3.238872
Within Groups	767.324	16	47.95775
Total	3139.19	19

c) Let us now interpret the result. The p-value of Between groups is much less than 0.05 also F-value is 16.4858 which is much greater than F-critical, so yes there is a significant difference in levels of Vitamin C content when measured day wise.

2) a) Scatter plot with trendline and R-square is below:

b) The equation is y = -5.6444x + 42.355. Putting x=2 we can get the Vitamin C value on day 2. Here y is Vitamin C and x number of days. So, Vitamin C on day =2 = -5.6444(2)+42.355 = 31.0662