A scientist was asked to test the effect of a new vitamin on rats. His hypothesis was that young rats that had vitamins added to their food would gain weight faster than young rats fed a normal diet. He predicted that if young rats were fed vitamins, they would gain more weight by the end of the experiment. He tested the effect of adding vitamins to some of the rats' diet by measuring the amount of weight each rat gained after three months. He then determined the average weight gained in each group. To analyze his results, he put the data he collected into the table shown below.

\begin{tabular}{|c|c|c|c|c|c|c|c|}
\hline
\multicolumn{4}{|c|}{Rats fed normal diet} & \multicolumn{4}{|c|}{Rats fed normal diet and vitamins} \\
\hline
Rat \# & \begin{tabular}{c}
Starting \\
weight
\end{tabular} & \begin{tabular}{c}
Ending \\
weight
\end{tabular} & \begin{tabular}{c}
Difference \\
in weight
\end{tabular} & Rat \# & \begin{tabular}{c}
Starting \\
weight
\end{tabular} & \begin{tabular}{c}
Ending \\
weight
\end{tabular} & \begin{tabular}{c}
Difference \\
in weight
\end{tabular} \\
\hline
1 & [tex]$256 g$[/tex] & [tex]$320 g$[/tex] & [tex]$64 g$[/tex] & 1 & [tex]$249 g$[/tex] & [tex]$342 g$[/tex] & [tex]$93 g$[/tex] \\
\hline
2 & [tex]$274 g$[/tex] & [tex]$347 g$[/tex] & [tex]$73 g$[/tex] & 2 & [tex]$221 g$[/tex] & [tex]$307 g$[/tex] & [tex]$86 g$[/tex] \\
\hline
3 & [tex]$209 g$[/tex] & [tex]$268 g$[/tex] & [tex]$59 g$[/tex] & 3 & [tex]$278 g$[/tex] & [tex]$381 g$[/tex] & [tex]$103 g$[/tex] \\
\hline
\begin{tabular}{c}
Average \\
weight gain
\end{tabular} & & & [tex]$65 g$[/tex] & \begin{tabular}{c}
Average \\
weight gain
\end{tabular} & & & [tex]$94 g$[/tex] \\
\hline
\end{tabular}

How did the experiment test the hypothesis?



Answer :

The experiment tested the hypothesis by comparing the weight gain of two groups of young rats over a period of three months. One group was fed a normal diet, while the other group was fed a normal diet plus added vitamins. The weight gain for each rat in both groups was recorded and then the average weight gain for each group was calculated.

Detailed steps to analyze the results are as follows:

1. Initial Data Collection:
- Three young rats were fed a normal diet. Their starting weights were recorded as 256 grams, 274 grams, and 209 grams.
- Three young rats were fed a normal diet with added vitamins. Their starting weights were recorded as 249 grams, 221 grams, and 278 grams.

2. Final Weights Measurement:
- After three months, the ending weights for the rats fed a normal diet were recorded as 320 grams, 347 grams, and 268 grams.
- For the rats fed a normal diet with added vitamins, the ending weights were recorded as 342 grams, 307 grams, and 381 grams.

3. Calculating Weight Gain:
- The weight gain for each rat in the normal diet group is calculated by subtracting the starting weight from the ending weight:
- For the first rat: 320g (ending weight) - 256g (starting weight) = 64g
- For the second rat: 347g - 274g = 73g
- For the third rat: 268g - 209g = 59g
- Similarly, the weight gain for each rat in the vitamins diet group is calculated:
- For the first rat: 342g - 249g = 93g
- For the second rat: 307g - 221g = 86g
- For the third rat: 381g - 278g = 103g

4. Average Weight Gain Calculation:
- The average weight gain for the normal diet group is calculated by summing the individual weight gains and dividing by the number of rats:
- (64g + 73g + 59g) / 3 = 65.33g
- The average weight gain for the vitamins diet group is calculated in the same way:
- (93g + 86g + 103g) / 3 = 94.0g

5. Comparing the Results:
- The average weight gain for the rats fed a normal diet is 65.33 grams.
- The average weight gain for the rats fed a normal diet plus vitamins is 94.0 grams.

Conclusion:
The experiment supported the scientist's hypothesis. The young rats that had vitamins added to their diet gained more weight on average (94.0 grams) compared to the rats fed a normal diet (65.33 grams). This suggests that adding vitamins to the diet may contribute to faster weight gain in young rats.