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lubasha [3.4K]
4 years ago
13

Is this correct or no(Direct answer please

Mathematics
1 answer:
ehidna [41]4 years ago
6 0
Yes, I believe this is correct.
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The rate of change of the mass, A, of salt at time t is proportional to the square of the mass of salt present at time t. Initia
Brums [2.3K]

Answer:

(a) -dA/dt = kA², A₀ = 10

(b) A =10/(1+ kt)

(c) t > 60 h

Step-by-step explanation:

(a) Find the IVP

A differential equation with an initial condition y₀ = f(x₀) is called an initial value problem.

The rate of decrease of A is proportional to A², and A₀ = 10, so the IVP is

-dA/dt = kA², A₀ = 10

(b) Solve the IVP

\begin{array}{rcl}-\dfrac{\text{d}A}{\text{d}t} & = & kA^{2}\\\\\dfrac{\text{d}A}{A^{2}} & =&-k\text{d}t\\\\-\dfrac{1}{A} & = & -kt + C\\\\\dfrac{1}{A} & = & kt + C\\\\\end{array}

Apply the initial condition: A₀ = 10 (when t = 0)

\dfrac{1}{10} = C\\\\\dfrac{1}{A} = kt + \dfrac{1}{10}\\\\\dfrac{10}{A} = 10kt + 1\\\\\mathbf{A} = \mathbf{\dfrac{10}{1+ kt}}

(c) Find the time when A(t) < 1

(i) Find the value of k (A₁₀ = 4)

\begin{array}{rcl}A& =&\dfrac{10}{1+ kt}\\\\4 & =& \dfrac{10}{1 + 10k}\\\\4 + 40 k & = & 10\\\\40k & = & 6\\k & = & 0.15\\\end{array}\\\\\mathbf{A} =\mathbf{ \dfrac{10}{0.15t + 1}}

(ii) Find t when A < 1

\begin{array}{rcl}A(t) & < & 1\\\dfrac{10}{0.15t + 1} & < & 1\\\\10 & < & 0.15t + 1\\9 & < & 0.15t\\t & > & 60\\\\\end{array}\\\mathbf{A < 1} \textbf{ when }\mathbf{ t >60}

The figure below shows the graph of A vs t.

6 0
3 years ago
An experiment was conducted to examine two different memorization methods to see which method allows people to remember better.
wlad13 [49]

Question Completion:

SubID  Memory1     Memory2

1                 71                78

2               75                75

3               77                82

4               90                91

5               72                90

6               79                 81

7               84                 75

8               75                 86

9               85                 92

10              75                 77

11               72                 92

12               76                87

13               77                93

14               90                94

15               84                78

16               73                92

17               75                85

18               87                86

19               75               95

20              70               94

21               72               75

22              90               84

23               81               94

24               87               82

25              90               82

26              87               79

27              78               94

28              78               79

29              70               82

30               81               80

31               80               78

32              90               87

33              83               90

34               81               85

35              73               88

36              82               82

37              84               94

38              85               86

39              77               94

40               82              83

Answer:

Since the mean of Memory1 (reciting method) (79.8) is smaller than the mean of Memory2 (imagery method) (85.5), we can conclude that there is a significant difference in memory performance between the reciting method and the imagery method.

Step-by-step explanation:

a) Data and Calculations:

SubID  Memory1     Memory2

1                 71                78

2               75                75

3               77                82

4               90                91

5               72               90

6               79                81

7               84                75

8               75                86

9               85                92

10              75                77

11               72                92

12              76               87

13              77               93

14              90               94

15              84               78

16              73               92

17              75               85

18              87               86

19              75               95

20             70               94

21              72               75

22             90               84

23              81               94

24             87               82

25            90               82

26             87               79

27             78               94

28             78               79

29             70               82

30              81               80

31              80               78

32             90               87

33             83               90

34              81               85

35             73               88

36             82               82

37             84               94

38             85               86

39             77               94

40             82               83

Total     3,193          3,421

Mean     79.8            85.5

Difference in means = 5.7 (85.5 - 79.8)

7 0
3 years ago
Hawthorne Middle School has 198 laptops
VashaNatasha [74]

Answer: 84 over 25 is 3.36 as your answer

5 0
4 years ago
Mrs. Ferree spent $43.50 on BBQ from The Smoke Station. The sales tax rate is 8%. What was her TOTAL cost?
AveGali [126]

Answer:

46.98

Step-by-step explanation:

Multiply the total without taxes by the taxes sales rate:

43.50 x 1.08

=46.98

7 0
3 years ago
Read 2 more answers
Please help me?? Solve for x
Delvig [45]
X= 10

This is because 180-95= 85 which would make 8x+5= 85

Subtract 5 from both sides and get 8x=80

Then, divide 8 from both sides and get x=10
3 0
3 years ago
Read 2 more answers
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