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Sonbull [250]
2 years ago
10

You are a researcher studying the lifespan of a certain species of bacteria. A preliminary sample of 30 bacteria reveals a sampl

e mean of x=74 hours with a standard deviation of s=5.4 hours. You would like to estimate the mean lifespan for this species of bacteria to within a margin of error of 0.65 hours at a 99% level of confidence.
What sample size should you gather to achieve a 0.65 hour margin of error? Round your answer up to the nearest whole number.
Mathematics
1 answer:
Diano4ka-milaya [45]2 years ago
5 0

Answer:

458

Step-by-step explanation:

Margin of error = critical value × standard error

At 99% confidence, the critical value is z = 2.576.

The standard error is σ/√n = 5.4/√n.

Given the desired margin of error is 0.65:

0.65 = 2.576 × 5.4/√n

n = 458

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Answer:

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Step-by-step explanation:

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Which of these are factors of 121?
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11 Bc 11 times 11 = 121
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A discuss moves from P1 (4,8) to P2 (15,17). What is the lincar displacement in the horizontal and vertical directions? What is
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Answer:

The horizontal displacement is 11 units, the vertical displacement is 9 units, and the projection angle is 39.3 degrees.

Step-by-step explanation:

We can start using the definition of displacement in one dimension between any 2 points which is the difference between them, so we have

\Delta s = s_2-s_1

And apply it to get the horizontal and vertical displacements.

Once we have found them, we can use trigonometric functions to find the projection angle with respect the horizontal.

Linear displacements.

Using the definition of displacement, we can write the horizontal displacement as

\Delta x = x_2-x_1

So we can use the given points P1:(x_1,y_2)  \text{  and  } P_2: (x_2,y_2) on the displacement formula

\Delta x = 15-4\\\Delta x = 11

In the same manner we can look at the y components of those points to find the vertical displacement

\Delta y = 17-8\\\Delta y =9

Thus the horizontal displacement is 11 units and the vertical displacement is 9 units.

Projection angle.

The projection angle with respect the horizontal is the angle that is made between the line that connects the points P1 and P2 and the horizontal, so we can use the linear displacements previously found to write

\tan(\theta) = \cfrac{\Delta y}{\Delta x}

Solving for the angle we get

\theta = \tan^{-1}\left(\cfrac{\Delta y}{\Delta x}\right)

Replacing values

\theta = \tan^{-1}\left(\cfrac{9}{11}\right)

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\theta = 39.3^\circ

So the projection angle is 39.3 degrees.

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3 years ago
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To finish this problem, we add 0.003.  2.908 + 0.003 = 2.911, so 2.911 is the answer to this problem.
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