Swimming records: The world record time for a certain swimming event was 63.2 seconds in 1950. Each year thereafter, the world record time decreased by 0.4 second. a. Use a formula to express the...

Swimming records: The world record time for a certain swimming event was 63.2 seconds in 1950. Each year thereafter, the world record time decreased by 0.4 second.

a. Use a formula to express the world record time as a function of the time since 1950. Be sure to explain the meaning of the letters you choose and the units.

b. Express using functional notation the world record time in the year 1955, and then calculate that value.

 c. Would you expect the formula to be valid indefinitely? Be sure to explain your answer.