function W(x)=60(5/6)^x , where x is the number of weeks that pass. How many word will the student remember after 3 weeks?

Question

Ms. Klemperer told her English class that each week students tend to forget one sixth of the vocabulary word they learned in the previous week. Suppose a student learns 60 words. The number of the words remembered can be described by function W(x) = 60 • (5/6)^x , where x is the number of weeks that pass. How many word will the student remember after 3 weeks?

Answer 1

Just plug x = 3 into the given equation.

 

W(x) = 60 (5/6)^x

 

W(3) = 60 (5/6)³ ≅ 34.7

 

Since the student cannot remember a fraction of a word, you have to decide whether to round down or round up.

Answer 2

60(5/6)³ = 60(5³/6³) = 60(125/216) = 34.7

 

Approximately 35 words will be remembered after 3 weeks