14.34 How many corn plants is too many? How much corn per acre should a farmer plant to obtain the highest yield? To find the best planting rate, do an experiment: plant at different rates on several plots of ground and measure the harvest. Here are data from such an experiment:
(a) Is yield or planting rate the explanatory variable? Why?
(b) Make a scatterplot of yield and planting rate.
(c) Describe the overall pattern of the relationship. Is it a straight line? Is there a positive or negative association, or neither? Explain why increasing the number of plants per acre of ground has the effect that your graph shows.
| Plants per acre |
Yield (bushels per acre) |
|||
| 12,000 | 150.1 | 113.0 | 118.4 | 142.6 |
| 16,000 | 166.9 | 120.7 | 135.2 | 149.8 |
| 20,000 | 165.3 | 130.1 | 139.6 | 149.9 |
| 24,000 | 134.7 | 138.4 | 156.1 | |
| 28,000 | 119.0 | 150.5 | ||