Question

HELP!!!!!!!
A certain type of parasite measures .0012 mm on its first day of life. It then triples in length each day after that. How many days will it take for the parasite to grow to be 150 mm?

A. About 5.1 days
B. About 10.7 days
C. About 49.9 days
D. About 41,666.7 days

Answer 1

HELP PLZ!

Answer 2

let the no. of. days be "x"..

Answer 3

can u frame an eq for this problem?

Answer 4

If you frame one for me i might be able to solve it

Answer 5

ok then..on the first day it is 0.0012..on the second day it is 3*0.0012..on the third day it is 3*(3*0.0012)..and so on

Answer 6

do u notice a pattern here with the no of days..?

Answer 7

So there is an increase of ( what ) from each term to the next? Phrased differently, is there a factor that will take you from the parasite's length one day to its length on the next day?

Answer 8

when x=1 0.0012
x=2 3^1(0.0012)
x=3 3^2(0.0012)

Answer 9

Write a model for the length of the parasite. L=(?) (?) ^ (?)

Answer 10

That answer is definitely D right? @priyar @mathmale

Answer 11

how can u tell?

Answer 12

if the day starts from 0 instead of one the eq will be of the form...150= 3^x..now find x

Answer 13

By testing your own equation. Does it correctly predict length after a given number of days?

Answer 14

sorry typing error..it is 150=0.0012(3^x)

Answer 15

Assuming that this model is correct, how would you solve for time, x?
Hint: What is the inverse function of the exponential function 3^x?

Answer 16

D is wrong @lilkg77 ..try solving for x...first divide by 0.0012 on both sides..what do u get?

Answer 17

sorry the eq is: 150=0.0012*(x^3) coz in the q it says triples and not three times..

Answer 18

now divide by 0.0012 on both sides..

Answer 19

what do u get @lilkg77 ? pls respond..

Answer 20

??

Answer 21

anyway u get 125000=x^3..so what is x?

Answer 22

ok..x=50 since 50*50*50=125000..so what will be the answer @lilkg77 ??

Answer 23

Sorry @priyar i was in using the bathrooom

Answer 24

The answer would be C @priyar

Answer 25

HI!!

Answer 26

its ok..and u are correct! did u understand?

Answer 27

Yeah thanks! @priyar

Answer 28

i do not think it is C

Answer 29

? @misty1212

Answer 30

it is not \[150=.0012\times x^3\] it is \[150=.0012\times 3^x\]

Answer 31

you need logs to solve this

Answer 32

divide by .0012 is the first step

Answer 33

@misty1212 even i thought so at first!(scroll up) but they have given "triples" and not "three times"

Answer 34

triples yes

Answer 35

1, 3, 9, 27, 81,...

Answer 36

\[125,000=3^x\\
x=\frac{\ln(125000)}{\ln(3)}\] and a calculator

Answer 37

or you can solve it directly using wolfram
http://www.wolframalpha.com/input/?i=150%3D.0012*3%5Ex