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Schach [20]
2 years ago
15

The amount of a sample remaining after t days is given by the equation P(t)=A(1/2)^(t/h), where A is the initial amount of the s

ample and h is the half-life, in days, of the substance. A sample contains 18% of its original amount of Radon-222. The half-life of Radon-222 is about 3.8 days. Which is the best estimate for the age of the sample?
Mathematics
2 answers:
s344n2d4d5 [400]2 years ago
5 0
The equation is:
P ( t ) = A * (1/2 )^(t/h)
If a sample contains 18% of the original amount of Radon - 222 and h = 3.8:
0.18 * A = A * ( 0.5 )^(t/3.8)   / : A ( we will divide both sides of the equation by A )
0.18 = ( 0.5 )^(t/3.8)
t/3.8 = log _{1/2}0.18
t / 3.8 = 2.47 ≈ 2.5
t = 3.8 * 2.5 = 9.5
Answer:
The best estimate for the age of the sample is 9.5 days.

S_A_V [24]2 years ago
5 0

Answer:

c. 9.4 days

Step-by-step explanation:

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Jada’s babysitter is four times Jada’s current age. In 5 years, Jada will be half her babysitter’s current age.
lora16 [44]

Answer:

24

Step-by-step explanation:

7 0
2 years ago
At 11:00 a.M., there are 400 members and 150 non-members visiting a museum. After 11:00 a.M., 10 members leave every five minute
alexdok [17]

Answer:

16:27

Step-by-step explanation:

GIVEN: At 11:00\text{ A.M.}, there are 400 members and 150 non-members visiting a museum. After 11:00\text{ A.M.},  10 members leave every five minutes and 5 non-members arrive every five minutes.

TO FIND: ratio of members to non-members at 1:00\text{ P.M.}

SOLUTION:

Total number of members in museum at 11:00\text{ A.M.} =400

as after every 5 minutes 10 members leave

total number of  5 minutes interval in 2 hour =\frac{60}{5}=12

total members at  1:00\text{ P.M.}  =400-10\times24

                                                =160

Total number of non-members in museum at  11:00\text{ A.M.} =150

as after every 5 minutes 5 non-members arrive

total number of  5 minutes interval in 2 hour =\frac{60}{5}=12

total non-members at  1:00\text{ P.M.}  =150+5\times24

                                                        =270

ratio of members to non-members at   1:00\text{ P.M.}  =\frac{\text{number of members}}{\text{number of non-members}}

                                                                                  =\frac{160}{270}

                                                                                  =\frac{16}{27}

Hence the ratio of members to non-members at 1:00\text{ P.M.} is \frac{16}{27}

5 0
2 years ago
The following histogram shows the relative frequencies of the heights, recorded to the nearest inch, of a population of women. T
Airida [17]

Answer:

The following histogram shows the relative frequencies of the height recorded to the nearest inch of population of women the mean of the population is 64.97 inches and the standard deviation is 2.66 inches

(a) Based on the histogram, what is the probability that the selected woman will have a height of at least 67 inches? Show your work

Answer:

0.22268

Step-by-step explanation:

z-score is z = (x-μ)/σ,

where x is the raw score

μ is the population mean

σ is the population standard deviation.

(a) Based on the histogram, what is the probability that the selected woman will have a height of at least 67 inches? Show your work

At least means equal to or greater than 67 inches

z = 67 - 64.97/2.66

z = 0.76316

P-value from Z-Table:

P(x<67) = 0.77732

P(x>67) = 1 - P(x<67) = 0.22268

The probability that the selected woman will have a height of at least 67 inches is 0.22268

Step-by-step explanation:

6 0
2 years ago
A pharmacy uses 4×10−3 liter of an active ingredient in one dose of a medication. The active ingredient comes in a 2-liter bottl
Firlakuza [10]
Since each bottle is made up of 2-liter of the active solution, in order to determine the number of doses of the medication that can be made, we just have to divide 2 L by 4x10^-3.
                  number of doses = (2 L) / (4x10^-3L/dose) = 500 doses
Therefore, the pharmacy can make 500 doses of the medication. 
3 0
2 years ago
Mr.Foote placed a cement walk along the side of his house. The walk if 18 inches wide and 32 feet long. What was the cost of the
Sonja [21]

we know that

1 ft-------> is equal to 12 in


step 1

find the area of the walk

18 in wide--------> convert to ft

18/12=1.5 ft

area=1.5*32------> 48 ft²


step 2

find the cost at $2.10 a square foot

multiply 48 ft² by $2.10

48*2.1=$100.80


therefore


the answer is

$100.80


5 0
2 years ago
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