Question

really need help understanding a concept! Please! I will give medal

Answer 1

I need help with half life!

Answer 2

lol, midlife crises?

Answer 3

hahaha no not midlife crisis! A radioisptope has a half life of 4 days. How much of a 20gram sample of this radioisotope remains at the end of 4 days

Answer 4

if it takes 4 years for something to reduce by half

then in 8 years it reduces by 1/2 + (1/2)/2

then in 12 years it reduces by 1/2 + 1/4 + (1/4)/2

etc .... it produces an exponential decay

Answer 5

if its half life is 4 days, then after 4 days there is half of it left

Answer 6

I don't get it for some reason ;/
so what would the equation look like?

Answer 7

20/2

Answer 8

if it takes you 5 hours to walk halfway home, then how far from home are you after you walk for 5 hours?

Answer 9

5 hours

Answer 10

well, halfway of course ... if your started 16 miles away then you have 8 miles left to go

Answer 11

if you start with 20 grams of something, and half of it is gone after 4 hours

then how much of the stuff is left after 4 hours?

Answer 12

ohhh 10 grams!

Answer 13

yep

lets say you measure it at 4 hours and its 10 grams, after another 4 hours its reduced by half again .... how much is left after that extra 4 hours?

Answer 14

5

Answer 15

correct

Answer 16

so we go from:

20 at 0 hours
10 at 4 hours
5 at 8 hours
2.5 at 12 hours
1.25 at 16 hours

every 4 hours it reduces by half

Answer 17

how many 3.8 days are in 23 days?

Answer 18

this one seems so much harder ;/

Answer 19

then we can brute it out 6 times

k at 0 periods
k/2 at 1 period
k/4 at 2 periods
k/8 at 3 periods
...

seems to be k/2^n for n periods

Answer 20

73.9/2^6 ... gives us what?

Answer 21

yep, but if we want to get real fancy we can simply wait till the end to approximate giving us:\[\large \frac{73.9}{2^{23/3.8}}=1.11332....\]

Answer 22

so at the end of 6 periods we are at 1.15 ... a little more gets us to 1.11 since its just a tad more than 6 periods

Answer 23

ohhh okay! gosh that simplifies it so much more! Thank you thank you! for your time

Answer 24

youre welcome