4. [5 marks] Psychologists sometimes use the function L = 200(1 - 64/10") to measure the number of vocabulary words L learned after t minutes. Note that L is a. one-to-one function. (3.) Find t as a. function of L. Explain the meaning of this inverse function. f (b) Using the ruult in part. (b), how long will it. take a. psychologist's subject to [earn 20 vocabulary words? Results may be rounded to 1 decimal place