Answer:
3.85 hours
Step-by-step explanation:
We have that the model equation in this case would be of the following type, being "and" the concentration of bacteria:
y = a * e ^ (b * t)
where a and b are constants and t is time.
We know that when the time is 0, we know that there are 100,000 bacteria, therefore:
100000 = a * e ^ (b * 0)
100000 = a * 1
a = 100000
they tell us that when the time is 2 hours, the amount doubles, that is:
200000 = a * e ^ (b * 2)
already knowing that a equals 100,000
e ^ (b * 2) = 2
b * 2 = ln 2
b = (ln 2) / 2
b = 0.3465
Having the value of the constants, we will calculate the value of the time when there are 380000, that is:
380000 = 100000 * (e ^ 0.3465 * t)
3.8 = e ^ 0.3465 * t
ln 3.8 = 0.3465 * t
t = 1.335 / 0.3465
t = 3.85
That is to say that in order to reach this concentration 3.85 hours must pass
A = 1/2(8+4)(3)
A = 6 * 3
A = 18
answer
<span>18 square yards</span>
Answer:
13
Step-by-step explanation:
The diagonals of a rectangle are congruent.
Her school is 2/3 miles away
2/3=4/6miles
So we need to find out how long it will take for her to run home from school...
School=4/6 miles
In 1 minutes she can run 1/6 miles
1min=1/6miles
In 2 minutes she can run 1/6+1/6 miles (1/6+1/6=2/6)
2min=2/6miles
3min=3/6miles
4min=4/6miles
It will take Erica 4 minutes to run 4/6 miles, so it'll take her 4 minutes to get home.
We can let r be the number of food tickets and f be the number of food tickets.
Since Alana can spend at most $40, that means the total of price bought for r and f must be less than or equal to $40. In addition, since Alana buys at least 16 tickets, this also means that the total of r and f is 16. Mathematically, we have these inequalities:
(1) 4r + 2f ≤ 40 and
(2) r + f ≥ 16
Multiplying -2 in (2), we have
4r + 2f ≤ 40
-2r - 2f ≤ 32
Adding both inequalities,
2r ≤ 8
r ≤ 4
Since r must be less than or equal to 4.Thus the answer is <span>A.</span>
