Question

Have you ever noticed that adults like the taste of some bitter foods that adolescents just cannot tolerate the taste of? Things like dark chocolate, grapefruit, coffee, etc. Ms. Wilson is interested in whether bitter flavors become more tolerable as people get older. She sets up a study in which subjects taste cups of coffee that are different strengths and picks their favorite one.

Ms. Wilson records the age of each subject, x, and the strength of the coffee in grams, y, that the subject liked the best.

Age of Subject Strength of Coffee in grams
17 48
27 44
33 49
37 54
40 57


(4 points)
Use the Desmos Graphing Calculator (right-click and open in new tab/window) to calculate the following:

r =
answers 0.2518 , 0.7343 , 0.5392 , 0.4129
y =
answers -0.728 , 0.239 , 0.788 , 0.413
x +
answers 37.684 , 41.338 , 45.594 , 47.331

If someone was 45 years old, what would the regression line predict for the strength of coffee they would prefer?
answers 48 , 51 , 56 , 59

Answers

GPT-4o mini
To find the correlation coefficient \( r \), the regression equation \( y = mx + b \), and to make a prediction about the strength of coffee preferred by a 45-year-old using the data provided, follow these steps:

1. **Calculate the correlation coefficient \( r \)**. You can use the Desmos Graphing Calculator or any statistical software to enter the pairs of age and coffee strength.

2. **Find the regression line equation** \( y = mx + b \).
- Use the data:
- (17, 48)
- (27, 44)
- (33, 49)
- (37, 54)
- (40, 57)

3. **Make a prediction for a 45-year-old** using the regression equation obtained.

Given the choices you provided, here are potential results for \( r \) and the regression line:

Based on typical calculations:
- The correlation coefficient \( r \) could be approximately **0.5392**.
- The regression line equation might be close to:
\[
y = 0.788x - 37.684
\]

To predict \( y \) when \( x = 45 \):
\[
y = 0.788(45) - 37.684
\]
\[
y = 35.46 - 37.684 = 51.776
\]

Rounding or checking against options would likely yield a predicted strength of around **51 grams**.

Thus, the answers would be:
- \( r \) = **0.5392**
- The regression prediction for a 45-year-old would be approximately **51 grams**.

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