SOLUTION: An unknown radioactive element decays into non-radioactive substances. In
700 days the radioactivity of a sample decreases by 29 percent.
(a) What is the half-life of the ele
Algebra.Com
Question 1143472: An unknown radioactive element decays into non-radioactive substances. In
700 days the radioactivity of a sample decreases by 29 percent.
(a) What is the half-life of the element?
half-life:
(days)
(b) How long will it take for a sample of
100mg to decay to 54mg?
time needed:
(days)
Found 2 solutions by josgarithmetic, greenestamps:
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
---------------------------------------------
In 700 days the radioactivity of a sample decreases by 29 percent.
----------------------------------------------
??
-
-
-
HALF-LIFE
1416
Answer by greenestamps(13200) (Show Source): You can put this solution on YOUR website!
The radioactivity does not decrease. What you mean is the amount of radioactive material decreases by 29%.
(a) calculating the half life....
(1) Determine the number of half lives required for the amount of radioactive material to decrease by 29% -- i.e., to decay to 71% of the original amount.
= 0.4941 to 4 decimal places
(2) Determine the half life, given that 700 days is 0.4941 half lives.
= 1416.69 days to 2 decimal places.
(a) ANSWER: the half life is 1416.69 days
(b) Determining the number of days for a sample of 100mg to decay to 54mg....
(1) Determine the number of half lives.
= 0.889 to 3 decimal places
(2) Determine the number of days in 0.889 half lives.
= 1259 to the nearest whole number
(b) ANSWER: about 1259 days for 100mg to decay to 54mg.
RELATED QUESTIONS
Please show step by step. Thanks
An unknown radioactive element decays into... (answered by josgarithmetic)
An unknown radioactive element decays into non-radioactive substances. In 560 days the... (answered by josgarithmetic,greenestamps)
An unknown radioactive element decays into non-radioactive substances. In 840 days the... (answered by rothauserc)
An unknown radioactive element decays into non-radioactive substances. In 820 days the... (answered by Fombitz)
Please help me with these problems. Thanks and show all work
1. A bank features a... (answered by solver91311)
If 250 mg of a radioactive element decays to 190 mg in 36hrs find the half-life of the... (answered by ikleyn)
A radioactive element decays at a rate of 7%. What is the half-life of the element (... (answered by ikleyn)
A certain radioactive element decays exponentially with a half-life of 5 hours. Find the... (answered by stanbon)
If 525 mg of a radioactive element decays to 400 mg in 48 hours, what is its... (answered by ankor@dixie-net.com)