Question

krusty was told that a new itching powder claims to cause 50% longer lasting itches. interested in this product, he buys the itching powder and compares it to his usual product. one test subject (a) is sprinkled with the original itching powder. another test subject (b) was sprinkled with the new experimental itching powder. his results are below. number of minutes itched subject a 30 minutes subject b 45 minutes identify the: 1. independent variable: 2. dependent variable: 3. what should krusty’s conclusion be? use data (numbers) to support your answer. 5. how could krusty improve his experiment?

Explanation:

Step1: Define independent variable

The variable that is changed or manipulated is the type of itching - powder.

Step2: Define dependent variable

The variable that is measured is the duration of itching.

Step3: Calculate percentage increase

To find the percentage increase in itching time for the new powder compared to the old one, use the formula $\frac{\text{New - Old}}{\text{Old}}\times100\%$. Here, Old = 30 minutes (Subject A) and New = 45 minutes (Subject B). So, $\frac{45 - 30}{30}\times100\%=\frac{15}{30}\times100\% = 50\%$.

Step4: Suggest experiment improvement

Using only one subject per group is not reliable. Increasing the number of subjects in each group would reduce the impact of individual differences.

Answer:

1. Type of itching powder
2. Duration of itching
3. The new itching powder causes 50% longer - lasting itches. Subject A itched for 30 minutes with the original powder and Subject B itched for 45 minutes with the new powder. Using the formula $\frac{45 - 30}{30}\times100\%=50\%$.
4. Increase the number of test subjects in each group to reduce the impact of individual variability.