How long will it take a radioactive
substance to decay to half of its original amount if it decays according to the
function A(t)=200e^-0.171t where t is the time in years?
A) 4.05 years
B)30.98 years
C)35.04 years
D) 34.20 years
Math Help?
2015-07-23 7:44 pm
回答 (2)
2015-07-23 7:50 pm
Needs parentheses: 200e^(-0.171t)
200 is the starting amount.
ending amount is ½ of 200 = 100
200e^(-0.171t) = 100
e^(-0.171t) = 0.5
-0.171t = ln(0.5)
t = -ln(0.5)/0.171 ≅ 4.05 years
200 is the starting amount.
ending amount is ½ of 200 = 100
200e^(-0.171t) = 100
e^(-0.171t) = 0.5
-0.171t = ln(0.5)
t = -ln(0.5)/0.171 ≅ 4.05 years
2015-07-23 7:51 pm
A) 4.05 years
A(t)= 100 = 0.5(200)
0.5= e^(-0.171t)
Ln 0.5= -0.171t
-0.69 =-0.171t
T = 4.05 years
A(t)= 100 = 0.5(200)
0.5= e^(-0.171t)
Ln 0.5= -0.171t
-0.69 =-0.171t
T = 4.05 years
收錄日期: 2021-04-21 12:01:19
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20150723114449AAXQKVA