- We are to find the time (number of minutes) is would take for 23 mg of the substance to be remaining.
- The formula for time is written as:
t = [t1/2 x In(Nt/No)] / In 2
where:
t1/2 = Half life = 4 minutes
No = Initial quantity of the sample = 90 mg
Nt = Amount of the sample left = 23 mg
t = time elapsed = ?
Hence,
t = [4 x In (23/90)] / -In 2
t = 7.8731645610906 minutes
Approximately to the nearest hundredth = 7.87 minutes
Therefore, there will be 23mg of substance remaining after 7.87 minutes.
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Answer:
r ≈ 2.07
Step-by-step explanation:
Using the formula
C=2πr
Solving for r
r= C/2π = 13/2π ≈ 2.06901
