Question

Based on data, here is a regression line comparing the variables y = mass of a bar of soap in grams and x = number of days soap has been used: Predicted y = 78.5 – 1.8x. Choose the correct interpretation for the slope:
A. A brand-new bar of soap that has been used zero days will be approximately 78.5 grams.
B. For every gram in mass, the predicted number of days it takes to lose that mass is 1.8.
C. For every day the soap is used, the predicted mass of the soap will increase by 1.8 grams.
D. For every day the soap is used, the predicted mass of the soap will decrease by 1.8 grams.
E. For every gram in mass, the predicted number of days it takes to gain that mass is 1.8 days.

Answer 1

Answer:

D .For every day the soap is used, the predicted mass of the soap will decrease by 1.8 grams.

Step-by-step explanation:

The given regression equation is

Predicted y = 78.5 – 1.8x where,  y = mass of a bar of soap in grams and x = number of days soap has been used.

Here, slope=b=-1.8.

Slope depicts the unit increase in predicted variable due to change in independent variable.

The given slope -1.8 shows that due to change in number of days soap is used the predicted mass of the soap decreases by 1.8 units. So, we can say that "For every day the soap is used, the predicted mass of the soap will decrease by 1.8 grams".