Answer:
B.)8ft
Step-by-step explanation:
Set up a proportional to the roof slope:
2/5 = x/20
Cross multiply:
40/5 = 5x/5
x=8ft
Answer:
Gradient of A: 2
Gradient of B: -1
Step-by-step explanation:
Gradient = change in y/change in x
✔️Gradient of A using two points on line A, (2, 5) and (0, 1):
Gradient = (1 - 5)/(0 - 2) = -4/-2
Simplify
Gradient of A = 2
✔️Gradient of B using two points on line B, (0, 5) and (5, 0):
Gradient = (0 - 5)/(5 - 0) = -5/5
Simplify
Gradient of B = -1
Answer: 4 years
Step-by-step explanation:
A(0) has to be amount at start. Assume that's 5mg
Then A(t) = 5×(0.5)^(0.25t) = 5×2^(-t/4),
(also known as 5 exp(-λ t) with λ = ln(2)/4, incidentally).
We need to such that A(t) = 2.5mg, or 2^(-t/4) is 1/2, which happens when -t/4 is -1, or t is 4.
