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Paul [167]
3 years ago
9

A sample of bacteria is decaying according to a half-life model. If the sample begins with 800 bacteria, and after 13 minutes th

ere are 320 bacteria, after how many minutes will there be 15 bacteria remaining? Round your answer to the nearest whole number.
Mathematics
1 answer:
nikklg [1K]3 years ago
3 0

Answer:

56.42 minutes

Step-by-step explanation:

The initial sample= y0 = 800

After 13 minutes , amount = 320

Y= y0e-kt

320 = 800e-k(13)

320/800 = e-k13

0.4 = e-k13

In0.4 = -k13

-0.91629= -k13

0.07048= k

Y = 800e-0.07048t

Minutes when the bacterial present will be 15

15 = 800e-0.07048t

15/800= e-0.07048t

0.01875 = e-0.07048t

In 0.01875 = -0.07048t

-3.97656 = -0.07048t

-3.97656/-0.07048= t

56.42 = t

56.42 minutes

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It has been suggested that night shift-workers show more variability in their output levels than day workers (σ2N > σ2D). Bel
Murljashka [212]

Answer:

<em>Calculated |t |= 7.72 > 2.1314 at 0.05 level of significance </em>

<em>Null hypothesis is rejected </em>

<em> The night shift-workers show more variability in their output levels are greater than day workers </em>

Step-by-step explanation:

<u>Step(i):</u>-

Given first sample size n₁ = 9

Given mean of the first sample x₁⁻ = 520

Given sample variance of the first sample'S²₁' = = 38

Standard deviation of the first sample 'S₁' = √38 =6.16

Given second sample size n₂ = 8

Given mean of the second sample x₂⁻ = 540

Given sample variance of the second sample ( 'S²₂' = 20

Standard deviation of the second sample 'S₂' = √20 = 4.4712

<u><em>Step(ii):-</em></u>

<em>Null hypothesis :H₀:  σ²₁ =σ²₂</em>

<em>Alternative Hypothesis:H₁: σ²₁ > σ²₂</em>

<em>Test statistic </em>

<em>               </em>t = \frac{x^{-} _{1} - x^{-} _{2} }{\sqrt{\frac{S^2_{1} }{n_{1} }+\frac{S^2_{2} }{n_{2} }  } }<em></em>

<em>              </em>

            t = \frac{520 - 540 }{\sqrt{\frac{38 }{9 }+\frac{20 }{8 }  } }

           t =    - 7.72

          |t| = |- 7.72| = 7.72

Degrees of freedom

<em> ν = n₁ + n₂ -2 = 9 +8 -2 = 15</em>

<em>t₀.₀₅ = 2.1314</em>

<u><em>Final answer</em></u><em>:-</em>

<em>Calculated |t |= 7.72 > 2.1314 at 0.05 level of significance </em>

<em>Null hypothesis is rejected </em>

<em> The night shift-workers show more variability in their output levels are greater than day workers </em>

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Answer:8:30 PM (20:30) Previous Day

Step-by-step explanation:

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4 years ago
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viva [34]

Answer:

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son4ous [18]

#1

= 9

Let's solve your equation step-by-step.

8.88=4.44(x−7)

Step 1: Simplify both sides of the equation.

8.88=4.44(x−7)

8.88=(4.44)(x)+(4.44)(−7)(Distribute)

8.88=4.44x+−31.08

8.88=4.44x−31.08

Step 2: Flip the equation.

4.44x−31.08=8.88

Step 3: Add 31.08 to both sides.

4.44x−31.08+31.08=8.88+31.08

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Step 4: Divide both sides by 4.44.

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= y = -3

 

Step 1: Simplify both sides of the equation.  

Step 2: Subtract 2 from both sides.  

Step 3: Divide both sides by 5.

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Mrac [35]

Answer:

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Step-by-step explanation:

A linear line equals up to 180

A+D=180

Substitute 116 for A

116+D=180

Subtract 116 from both sides

D=64

A reflection across the x-axis won't change the measure of an angle

The answer is 64.

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