Part 1 of 3 - Project 4

A recently manufactured additive was added to pellets that Wistar rats (Rattus norvegicus) are fed. The manufacturer claims that this additive results in faster growth, hence faster maturity (and hence, a shorter breeding time) of these rats. A laboratory that breeds Wistar rats used in experiments recently purchased the pellets with the additive in them, in order to test this claim. One hundred and twenty Wistar rats were randomly selected out of a batch of 21-day old rats that were being bred at that current time in the laboratory. Sixty of these rats, 27 males and 33 females, were randomly placed into a group that then continued on a normal (existing) pellet diet (diet 1). The remaining sixty rats, 31 males and 29 females, were placed in a group that was started on the new pellets with an additive diet (diet 2). Before embarking on this experiment, all the rats had their body weights (in grams) and tail lengths (in millimetres) measured and recorded, and were all placed in individual cages, each receiving an equal amount of pellets daily. After 3 weeks, their body weights and tail lengths were again measured and recorded. From previous studies, it is known that it takes 7 weeks for Wistar rats (Rattus norvegicus) to reach sexual maturity, and the weight of the male rats at maturity would be between 450 - 550 grams, while that of female rats would be 250 - 300 grams. The tail lengths of both male and female adult rats would be 90 - 110 millimetres.

(source: https://www.mcgill.ca/cmarc/files/cmarc/handout_rat_module_1-sept_09_0.pdf)

Question 1 of 16

2.0 Points

What will be the main research question of this study?

A.Is there a difference in the growth rates of male and female Wistar rats?

B.

Do male Wistar rats grow faster than female Wistar rats?

C.

Are the tail lengths for male and female Wistar rats equal?

D.

Does the food additive cause growth in Wistar rats (Rattus norvegicus)?

E.

Does the inclusion of the new food additive in the diet of Wistar rats (Rattus norvegicus) result in faster growth?

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Question 2 of 16

2.0 Points

Apart from body weights and tail lengths, what other 2 main variables of interest can be used in measuring growth of rats?

A.

Length of front teeth and colour.

B.Craniofacial measurements and fur hair length.

C.

Craniofacial measurements and growth plate of the proximal tibia.

D.Growth plate of the proximal tibia and Colour.

E.Fur hair length and length of front teeth.

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Question 3 of 16

1.0 Points

What type of data will be recorded from variables of your study?

A.Categorical

B.

Continuous

C.

Nominal

D.Discrete

E.Ordinal

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Question 4 of 16

1.0 Points

Select the correct null hypothesis for your study based on the data provided.

A.There is no growth in female Wistar rats on diet 1 as well as female Wistar rats on diet 2.

B.

The mean tail length of female Wistar rats on diet 1 is the same/equal to the mean tail length of female Wistar rats on diet 2.

C.The mean tail length of female Wistar rats on diet 1 is the not equal to the mean tail length of female Wistar rats on diet 2.

D.

The tail length of female Wistar rats on diet 1 is the not equal to the tail length of female Wistar rats on diet 2.

E.The tail length of female Wistar rats on diet 1 is the same/equal to the tail length of female Wistar rats on diet 2.

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Question 5 of 16

2.0 Points

What 2 graphs would be the appropriate to summarize data provided for your study?

A.

Box-and-whiskers plots, bar graphs

B.

Box-and-whiskers plots, Steam-and-leaf plots

C.bar graphs, pie charts

D.

Histograms, pie charts

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