<span> half life i= 78 hours
amount after 78 hours is 395 kg:
395 = 790e^(k*78)
Dividing by 790 and taking natural log
ln (395/790) = (k*78)
-0.6931 = 78k
-0.00888 = k
lets calculate how much is left after 18 hours:
Amount(18)
= 790e^(-0.00888*18)
Amount = 673.301 kg
hope this helps</span>
Assume the parabola is placed on a graph where the x-axis is the top of the dish.
The vertex is then at (0,-30) The x-intercepts or zeros are at (-30,0) and (30,0)
The equation of such parabola would be:
Plug in vertex to find value of 'a'
Now find the focus given that
Answer: the microphone should be placed 7.5 inches from vertex.
Steps to Solve:
29.3 = 1.7y
29.3/1.7 = 1.7y/1.7
y = 17.2352941176
In this case, we round up the hundredths place because the number in the thousandths place is 5 or higher.
y = 17.24
Hope this helps!! :)
Idk I just need to answer some more questions