Question

A store had 250 bottles of water. Each week, 40% of the bottles were sold and 48 new bottles arrived in shipments. Which recursive function best represents the number of bottles of water in the store, given that f(0) = 250?

Answer 1

(A) f(n) = f(n - 1) * 0.6 + 48, n > 0
(B) f(n) = 250 - f(n - 1) * 0.4 + 48, n > 0
(C) f(n) = f(n - 1) * 0.4 + 48, n > 0
(D) f(n) = 250 - f(n - 1) * 0.6 + 48, n > 0

Answer 2

The answer is not C or B. Is it D?

Answer 3

Hint as 40% are sold this leaves 60% or 0.60

Answer 4

Oh, ok. That completely rules out B and C. We are left with A and D.

Answer 5

But why?

Answer 6

we start with 250

substituting n = 1,2 and 3 in B

Answer 7

try that

Answer 8

ok give me some time.

Answer 9

250-f(1-1)*0.4+48 = 298?

Answer 10

f(1-1) = f(0) = 250

Answer 11

so its
250 - 0.4*250 + 48 = 198

Answer 12

Yeah okay. 250 - f(1-1) * 0.4 + 48 = 198

Answer 13

when n =2 what do you get

Answer 14

250 - f(2-1) * 0.4 + 48 = 98? I'm not sure on this

Answer 15

does f(2-1) = 100?

Answer 16

or does it equal to 500? or 150?

Answer 17

no f(1) = 198

Answer 18

How did u get 198?

Answer 19

we worked it out earlier one

Answer 20

actually it can't be B

Answer 21

Yeah that's what I said earlier lol

Answer 22

because we dont start with 250 every week

Answer 23

yes you were right

Answer 24

what about C?
dont forget f(0) = 250

Answer 25

It can't be C. I put that answer before and it was incorrect.

Answer 26

the book said its incorrect?

Answer 27

Not the book. the quiz on FLVS

Answer 28

yes its incorrect
A is the correct answer
because f(0) * 0.6 + 48 gives 150 + 48 = 198 for first week
which is then input to the next week

Answer 29

I saw that earlier but got confused myself
sorry

Answer 30

oh it's alright lol

Answer 31

I guess I'm tired!!

Answer 32

A is definitely correct

Answer 33

250 * 0.6 = 150 that's how u got that right?

Answer 34

yes - then add the 48

Answer 35

Yeah add the 48. Thank you so much! Hope you feel better.

Answer 36

ty yw

Answer 37

yw too