To answer your questions about the 100 m dash finishing times since 1960, we need to set up a hypothetical linear model for the data.
Part A: Let's assume that in 1960, the finishing time for the 100 m dash was approximately 10.6 seconds. This is an example figure and should be replaced with actual historical data if you have it.
Part B: Assuming we have a linear model represented by the equation \( y = mx + b \), where \( y \) is the finishing time, \( m \) is the slope, and \( x \) is the number of years since 1960, the slope \( m \) indicates the annual decrease in finishing time. If the slope is, for example, \( -0.02 \), this means the finishing time has decreased by 0.02 seconds each year.
Thus, the finishing time since 1960 has decreased each year by 0.02 seconds (using this hypothetical slope as an example).
Part C: If the model predicts a decrease of \( m \) seconds every year, then over 4 years, the decrease will be \( 4m \). Continuing with our example of \( m = -0.02 \):
\[ 4 \times (-0.02) = -0.08 \text{ seconds} \]
So the model predicts the first-place finishing time will decrease by 0.08 seconds every 4 years (based on our hypothetical example).
Please replace the example numbers with actual data if available.