I'm pretty sure that the answer is 13/40
Answer:
u trrahs at fritnote
Step-by-step explanation:
- 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.
To learn more, visit the link below:
brainly.com/question/16624562
The formula for a cone is pi * r^2 * (h/3) or pi* r^2 * h * 1/3.
Since the height is 7ft and the radius if 4ft you plug those into the equation and get:
V= 1/3 * pi * (4^2) * (7)ft cubed which is the answer of B
