Final answer:
The question does not provide the original price of the lawn sprinkler or the senior citizen discount rate, so we cannot calculate the final cost for Paul.
Step-by-step explanation:
To calculate the cost of a lawn sprinkler for Paul, who is a senior citizen purchasing on a Tuesday, we need additional information such as the original price of the lawn sprinkler and any possible discounts for senior citizens on Tuesdays.
However, this information is not provided in the question. Without the price of the lawn sprinkler and the discount details, it is not possible to determine the exact cost for Paul.