Question

Oil consumption is increasing at a rate of 1.9% per year. What is its doubling time?
I'm not sure if this is linear increase or exponential.
if its linear

Answer 1

, no , this website says its exponential
http://www.algebra.com/algebra/homework/logarithm/logarithm.faq.question.112025.html

Answer 2

, if its linear then
y = Ao ( 1 + .06*t )
if its exponential then
y = Ao ( 1 + .06)^t

Answer 3

i think its exponential
2 = 1 ( 1 + 0.06)^t
now calculate t

Answer 4

Oh, wait. That's right. I apologize. I graphed it wrong.

Answer 5

how will i know if its exponential or not?

Answer 6

here is another example
http://www.physics.uoguelph.ca/tutorials/exp/intro.html

Answer 7

why isnt the following example linear ?
"For example, let's look at a population of wee beasties which increases by 10% per year. If there were 100 wee beasties now, there would be an increase of 10 wee beasties after a year. "

Answer 8

see in question it increases 1.9% per year
first year let consumption = x
next year = 1.9*x/100
later year = 1.9(1.9*x/100)/100
if you plot its graph you get exponential curve
try it

Answer 9

in your second example
population first year = 100
population second year = 110
population third year = 121
it also not linear

Answer 10

you need a plus somewhere

Answer 11

it should be
next year consumption = last year consumption* ( 1 + 1.9/100)

Answer 12

yes you are write

Answer 13

so we have
x1 = x
x2 = x1 (1.019)
x3 = x2 (1.019) = [x1 (1.019) (1.019) ]

Answer 14

better start with zero,
x0 = x
x1 = x0 (1.019)
x2 = x1 (1.019) = [x0 (1.019) ] (1.019) = x0 (1.019) ^2

Answer 15

calculate x1,x2 ,x3
and try to find
x2 - x1 = x3 -x2
if its write then only its linear

Answer 16

so did you agree with my math?

Answer 17

right, clearly x2-x1 != x3 - x2

Answer 18

yes i agree
so what you think
its linear or exponential

Answer 19

well... exponential

Answer 20

i think its a little ambiguous however

Answer 21

, you could also have
y = x0 ( 1 + .019 * t ) , no ?

Answer 22

ok how would you word it so that it is linear?

Answer 23

let if increase every year is same then its linear
for example
if population of city inc by 20 people every year
then we can say that its linear

Answer 24

ok , so we wouldnt use percentage for a linear increase

Answer 25

yes

Answer 26

if there is a percentage growth , like population percentage growth , grows at a constant percentage, it is exponential growth

Answer 27

yes

Answer 28

got it,

Answer 29

ok then

Answer 30

ok now doubling time makes sense

Answer 31

doubling time is the time it takes for the initial amount to grow 100%
, leaving you with double

Answer 32

yes
did you get your answer?

Answer 33

yes, the math i didnt have trouble with. just the understanding

Answer 34

i have a much harder problem, differential equation

Answer 35

are you ready?

Answer 36

its a logistic growth problem

Answer 37

ok then
now you can close the qustion
after giving me medal...............lol

Answer 38

you stuck it out , good work

Answer 39

the rest bailed