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maksim [4K]
2 years ago
11

The amount of caffeine in the body of a healthy adult after drinking espresso decreases exponentially, with a half-life of appro

ximately 6 hours. That is, every 6 hours, the amount of caffeine in the body decreases by 50%. Charlotte wants to go to sleep at 11 pm and does not want more than 20 milligrams (mg) of caffeine in her system at that time. What is the latest time Charlotte can drink a 2-ounce shot of espresso that contains 80 mg of caffeine?
A. 5 am

B. 11 am

C. 11:30 am

D. 12 pm

Mathematics
2 answers:
yarga [219]2 years ago
7 0
After 6 hours the amount of caffeine 40 mg. After another 6 hours the amount of caffeine is 20 mg. It takes 12 hours for the total amount of caffeine to drop down to 20 mg. the answer is 11 am -B. Hope this helps!
Pachacha [2.7K]2 years ago
7 0
Please let me know if you have any questions!

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Christopher wrote the number pattern below.The first term is 8. 8,6,8,7,10
Aneli [31]
8 goes to 6 that’s -2 then goes back to 8 then goes to 7 that’s -1 add -1 and -2 and you get -3 but you add it like before so it’s 7 to 10 so then it’s 10 -4 to 6 then goes back to 10 to where you add 4 to get 14
4 0
1 year ago
Two cells are viewed and measured under a microscope. The approximate diameter
nikklg [1K]

Answer:

option D. 4.7 x 10-4 m

Step-by-step explanation:

<u><em>The correct question is</em></u>

• cell P: 5.0 x 10-4 meters

• cell Q: 3.0 x 10-5 meters

we have            

The diameter of cell P is  5*10^{-4}\ m

The diameter of cell Q is  3*10^{-5}\ m

Rewrite the diameter of cell P as    

5*10^{-4}\ m=5*10^{-4}(\frac{10}{10})=50*10^{-5}\ m

Find the difference

50*10^{-5}\ m-3*10^{-5}\ m=47*10^{-5}\ m

Rewrite the difference as

47*10^{-5}\ m=47*10^{-5}}(\frac{10}{10})=4.7*10^{-4}\ m

7 0
2 years ago
a motor boat traveled 18 miles down a river in 2 hours but took 4.5 hours to return upstream. Find the rate of the motor boat in
tangare [24]

Answer:

  • rate of the boat in still water = 6.5 miles / hour

  • rate of the current = 2.5 miles / hour.

Explanation:

<u>1) Name the two variables:</u>

  • c: rate of the current
  • b: rate of the boat in still water:

With that, the net rates of the boat down the river and upstrean are:

  • down the river: b + c
  • upstream: b - c

<u>2) Now set the equations for the distance as a function of the times and the rates:</u>

  • distance = rate × time

  • downstream: 18 miles = (b + c) × 2 hours
  • upstream: 18 miles = (b - c) × 4.5 hours

<u>3) Set the system of equations:</u>

  • 18 = 2(b + c) ⇒ 9 = b + c . .  . Equation (1)
  • 18 = 4.5 (b - c) ⇒ 4 = b - c . . . Equation (2)

<u>4) Solve the system by </u><u>elimination</u><u>:</u>

  • Add equations (1) and (2): 9 + 4 = 2b
  • Divide both sides by 2: 13/2 = b
  • Simplify: b = 6.5

  • Replace b with 6.5 in equation (2) and solve:

       4 = 6.5 - c ⇒ c = 6.5 - 4 = 2.5

<u>5) Results:</u>

  • b = rate of the boat in still water = 6.5 miles / hour

  • c = rate of the current = 2.5 miles / hour.

   

3 0
2 years ago
Read 2 more answers
A person recently read that 84% of cat owners are women. How large a sample should the researcher take if she wishes to be 90% c
Lana71 [14]

Answer:

405

Step-by-step explanation:

To find sample size, use the following equation, where n = sample size, za/2 = the critical value, p = probability of success, q = probability of failure, and E = margin of error.

n=\frac{(z_{\frac{\alpha }{2} })^{2} *p*q  }{E^2}

The values that are given are p = 0.84 and E = 0.03.

You can solve for the critical value which is equal to the z-score of  (1 - confidence level)/2.  Use the calculator function of invNorm to find the z-score.  The value will given with a negative sign, but you can ignore that.

(1 - 0.9) = 0.1/2 = 0.05

invNorm(0.05, 0, 1) = 1.645

You can also solve for q which is 1 - p.  For this problem q = 1 - 0.84 = 0.16

Plug the values into the equation and solve for n.

n =\frac{(1.645)^2*0.84*0.16}{(0.03)^2}\\n= 404.0997333

Round up to the next number, giving you 405.

6 0
2 years ago
Central school is hosting a “central has talent” show. They will award various prizes for the best 3 acts in the show. First pla
Serjik [45]
Well you didn't post the expressions but let X be the amount of money for first place. This means X-50 would be the amount of second place because <span>each subsequent place after 1st wins $50 less than the previous place. Thirds, would be X-50-50 or X-100

Thus the total amount of money would be all of the values combined which is X+X-50+X-100=3X-150
</span>
8 0
2 years ago
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