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

Answer 1

@imqwerty @

Answer 2

@xapproachesinfinity

Answer 3

look for the pattern

Answer 4

?

Answer 5

month of February we have 253 lets call that first month okay

Answer 6

ok

Answer 7

so month 1 we have 253
month 2 we 0.3x253+50
month 3 we have 0.3x(0.3x253+50)+50

Answer 8

lets see the pattern after n months

Answer 9

kk

Answer 10

or you could just check if those options work

Answer 11

check for first month n=1

Answer 12

oh they made n=0 the first month
not n=1 let's check for n=0 do we get 253 for what option

Answer 13

A?

Answer 14

oh well all of them actually have f(0)=253 for n=0
do n=1 and check

Answer 15

ok giv a sec

Answer 16

the right one has to have for n=1 f(1)=125.9

Answer 17

oh no error i used 253 instead of 235

Answer 18

for n=1 we should get f(1)=120.5 not 125.9 that was a mistake ok

Answer 19

ok

Answer 20

A and B or not good since they don't work out

Answer 21

same for D if you cheched

Answer 22

so C works as an answer

Answer 23

ok thank you

Answer 24

if you tried the find the pattern you would have gotten the same formula
doing month 0 we have 235
month 1 we have 0.3x235+50
month 2 we have 0.3x(0.3x235+50)+50
and so on....

Answer 25

f(0)=235
f(1)=0.3x235+50=0.3xf(0)
f(2)=0.3x(0.3x235+50)+50=0.3xf(1)+50
f(3)=0.3xf(2)+50
we go following the pattern tell n
f(n)=0.3xf(n-1)+50

Answer 26

@emogirl100