Question

9. A particular radioactive substance has a half-life of 3 years. Suppose an initial sample has a mass of 200 mg.
a) Write an equation that relates the mass of the radioactive material remaining to time.
b) How much will remain after one decade, to the nearest hundredth?

please do part b)

Answer 1

Af = Ao (1/2) ^ t/h

Answer 2

Af = 200 (1/2) ^ 10/3

i cant solve from here

Answer 3

punch it in the calculator.

i got 0.07; to the nearest hundredth

Answer 4

the answer is 19.84 mg

Answer 5

i got the answer too but i forgot how i did it

Answer 6

srry i know only grade 8 maths

Answer 7

h is the Planck's constant ryt ?

Answer 8

h is the half life period

Answer 9

half life means, it reduces to half in that period. So, from 200mg it goes to 100 mg in 3 years. In 6 years, it goes to 50 mg. In 9 years, it goes to 25 mg. In 10 years, it goes to.....that is the part of the equation I am not clear on (too long ago and too late/tired to recall).

Answer 10

Try 25mg to the power of 2/3. Is that 19.84mg? I don't have scientific calculator.

Answer 11

exactly but i gotta get the number 19.84. I got all the values just need to know how to put it in and no it doesnt work

Answer 12

i got it. .

Answer 13

Try...200*(1/2)^10/3

Answer 14

punch in the calculator the first equation u've given

Answer 15

@Jerwyn: how did you do it `:O

Answer 16

find the cube root of .5 to tenth power, then multiply to 200

Answer 17

My value is correct.

Answer 18

200 times (1/2) to the power of 10/3. It gives you 19.84.

Answer 19

First find 0.5 to the power of 3.333333.
Then multiply by 200.