A store had 235 MP3 players in the month of January. Every month, 30% of the MP3 players were sold and 50 new MP3 players were stocked in the store.

Which recursive function best represents the number of MP3 players in the store f(n) after n months?

f(n) = 0.7 × f(n - 1) + 50, f(0) = 235, n 0

f(n) = 237 - 0.7 × f(n - 1) + 50, f(0) = 235, n 0

f(n) = 0.3 × f(n - 1) + 50, f(0) = 235, n 0

f(n) = 237 + 0.7 × f(n - 1) + 50, f(0) = 235, n 0

Question

A store had 235 MP3 players in the month of January. Every month, 30% of the MP3 players were sold and 50 new MP3 players were stocked in the store.

Which recursive function best represents the number of MP3 players in the store f(n) after n months?

 f(n) = 0.7 × f(n - 1) + 50, f(0) = 235, n > 0

 f(n) = 237 - 0.7 × f(n - 1) + 50, f(0) = 235, n > 0

 f(n) = 0.3 × f(n - 1) + 50, f(0) = 235, n > 0

 f(n) = 237 + 0.7 × f(n - 1) + 50, f(0) = 235, n > 0

anonymous · Answer

every month 30% is sold
so remaining is (1-0.3)*235=0.7*235
every month 50 is added
so 0.7*235+50 is afterfirst month
so replace it by n months