Answer:
does not make sense
Step-by-step explanation:
For this case we have an equation of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: decrease rate
t: time in years.
Substituting values we have:
7 = A * (0.5) ^ ((1/20) * t)
For t = 45 years we have:
7 = A * (0.5) ^ ((1/20) * 45)
Clearing A:
A = 7 / ((0.5) ^ ((1/20) * 45))
A = 33.3
Answer:
the density of the substance when it was deposited 45 years ago was:
A = 33.3 milligrams per square centimeter
Refer to the diagram shown below. It shows a vertical cross-section of the paraboloid through its axis of symmetry.
Let the vertex of the parabola be at the origin. Then its equation is of the form
y = bx²
Because the parabola passes through (18,8), therefore
8 = b(18²)
b = 0.02469
The parabola is y = 0.02469x².
The receiver should be placed at the focal point of the paraboloid for optimal reception.
The y-coordinate of the focus is
a = 1/(4b) = 1/0.098765 = 10.125 in
Answer: The receiver is located at 10.125 inches from the vertex.
To find the mean you must add up all the numbers and divide by how many there are:
35 + 60 + x
_________ = 70
3
35 + 60 + x = 210
x = 65
He must score at least a 65 for a 70 average.