A(t) = Ao*e^(-rt)
-rt = ln [ A(t)/ Ao]
t = - ln [ A(t)/ Ao] / r
r= 0.0124% = 0.0124/100 = 0.000124
A(t)/A0 = 10% = 10/100 = 0.1
Now substitute
t = - ln [0.1] / 0.000124 = 2.3025851 / 0.000124 = 18,569 years
Your result will depend on how you round ln(0.1).
Correct option is A) [-13/4, 9/4] .
<u>Step-by-step explanation:</u>
Here we have following equation as |2 + 4x| = 11 or , 
. We need to solve for the value of x .Let's find out:
We know that Modulus Function is both positive & negative for particular values of x , i.e.
|2 + 4x| is positive :
⇒ 
⇒ 
⇒ 
⇒ 
|2 + 4x| is negative :
⇒
⇒ 
⇒ 
⇒ 
Therefore , Correct option is A) [-13/4, 9/4] .
Answer:
Me
Step-by-step explanation:
We have 55% and 80% antifreeze. We need 90 gallons of 75%.
F - 55% and E - 80%
A) F + E = 90
B) .55 F + .80 E = 67.50 (which is .75 * 90) Multiplying A) by -.55
A) -.55 F -.55 E = -49.50 (which is -.55 * 90) then adding A) & B)
.25 E = 18
E = 72 gallons of 80% and
F = 18 gallons of 55%
********* DOUBLE CHECK ******************
72 * .80 = 57.60 and 18 * .55 = 9.90
57.60 + 9.90 = 67.50 gallons of antifreeze and we have 90 total gallons
(67.50 / 90) * 100 = 75% correct!
Source: 1728.com/mixture.htm
