Question

Amanda exercised for 10 minutes every day in the first week, 20 minutes in the second week, 30 minutes in the third week, and 40 minutes in the fourth week.

Billy exercised for 5 minutes every day in the first week, 10 minutes in the second week, 20 minutes in the third week, and 40 minutes in the fourth week.

Which statement best describes the methods used by Amanda and Billy to increase the time they spent exercising?

Answer 1

(A) Amanda's method is linear because the number of minutes increased by an equal number every week.
(B) Billy's method is linear because the number of minutes increased by an equal factor every week.
(C) Both Billy's and Amanda's methods are exponential because the number of minutes increased by an equal factor every week.
(D) Both Billy's and Amanda's methods are exponential because the number of minutes increased by an equal number every week.

Answer 2

I need help on this question plz. @HelpBlahBlahBlah @hartnn @iambatman @kropot72 @KamiBug

Answer 3

I know that Amanda has an arithmetic sequence with a difference of 10. Billy has a geometric sequence with a constant ratio of 2.

Answer 4

But I don't know how those are described in the options above. -_-

Answer 5

@Godlovesme can u help me plz?

Answer 6

@Diyadiya @Directrix @Sadworld @Michele_Laino @One098 Can u guys plz help me out?

Answer 7

Can you have 2 answers?

Answer 8

no only 1; it's a multiple choice question on FLVS

Answer 9

If not, the answer would be D since both increase exponentially since the number of minuets increase by an equal number each week. Amanda by 10 and Billy by 2(x)

Answer 10

It can't be C see since Amanda's increase is not due to factors. A and B doesn't answer the question.

Answer 11

Oh, it's C. I just did the math.

Answer 12

mins of Billy are:
5-10-20-40
can they mamatize with a linear or proportional function?

Answer 13

note that:
10=2*5
20=2*10
40=2*20
so?
@happyrosy

Answer 14

linear function is if the pattern is the constant like
5,10,15,20 --> it increases with constant rate of 5 (+5)
and exponential is multiplication like
5,10,20,40 --> x2 each value
confused @happyrosy

Answer 15

So the linear function is Amanda's sequence?

Answer 16

yes :) what about billy's?

Answer 17

Billy's is exponential.

Answer 18

correct!!

Answer 19

So B, C, and D are ruled out right? Making A the correct answer.

Answer 20

what is the xponential function of Billy?

Answer 21

Billy's gets multiplied by 2 each time.

Answer 22

I think:\[5*2^{n}\]
where n is the number of the week

Answer 23

n=0, 1,2,3

Answer 24

Yeah that's another way because when n= 0, f(0) equals to 5

Answer 25

when n= 1, f(1) equals to 10...n= 2, f(n)= 20..and so on

Answer 26

you are right! @happyrosy
so I rewrite the function as below:
\[5*2^{n-1}\]
where n=1, 2, 3, 4

Answer 27

okay so would A be the answer then?

Answer 28

yes! I think so!

Answer 29

THANK YOU ALL FOR HELPING ME OUT!! :) I understood everything.

Answer 30

thank you! :) @happyrosy

Answer 31

anytime :) @happyrosy thanks for the medal

Answer 32

np :)