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Dafna1 [17]
3 years ago
11

A researcher compares the effectiveness of two different instructional methods for teaching electronics. A sample of 138 student

s using Method 1 produces a testing average of 61. A sample of 156 students using Method 2 produces a testing average of 64.6. Assume the standard deviation is known to be 18.53 for Method 1 and 13.43 for Method 2. Determine the 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2. Step 1 of 2: Find the critical value that should be used in constructing the confidence interval.
Mathematics
1 answer:
yan [13]3 years ago
5 0

Answer:

The 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 is (-8.04, 0.84).

Step-by-step explanation:

The (1 - <em>α</em>)% confidence interval for the difference between population means is:

CI=(\bar x_{1}-\bar x_{2})\pm z_{\alpha/2}\times \sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}

The information provided is as follows:

n_{1}= 138\\n_{2}=156\\\bar x_{1}=61\\\bar x_{2}=64.6\\\sigma_{1}=18.53\\\sigma_{2}=13.43

The critical value of <em>z</em> for 98% confidence level is,

z_{\alpha/2}=z_{0.02/2}=2.326

Compute the 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 as follows:

CI=(\bar x_{1}-\bar x_{2})\pm z_{\alpha/2}\times \sqrt{\frac{\sigma^{2}_{1}}{n_{1}}+\frac{\sigma^{2}_{2}}{n_{2}}}

     =(61-64.6)\pm 2.326\times\sqrt{\frac{(18.53)^{2}}{138}+\frac{(13.43)^{2}}{156}}\\\\=-3.6\pm 4.4404\\\\=(-8.0404, 0.8404)\\\\\approx (-8.04, 0.84)

Thus, the 98% confidence interval for the true difference between testing averages for students using Method 1 and students using Method 2 is (-8.04, 0.84).

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An angle measures 3.2° less than the measure of its complementary angle. What is the measure of each angle?
cupoosta [38]

Answer:

<h2>        43.4° and 46.6°</h2>

Step-by-step explanation:

x   - measure of angle

x + 3.2°   - measure of its complementary angle

Complementary angles adds to 90°

x + x + 3.2° = 90°

2x = 90° - 3.2°

2x = 86.8°

 x = 86.8°÷2

 x = 43.4°

x+3.2° = 43.4° + 3.2° = 46.6°

4 0
2 years ago
At Greenwood Landscaping, rock costs $47.50 per ton. How much would 2.5 tons cost?
Grace [21]

Answer:

Hey!

Your answer is $118.75!

Step-by-step explanation: How did I get this?

<u>STEP 1:</u> So we know that for a ton of rock costs us $47.50...

To get 2 tons all we have to do is to MULTIPLY $47.50 by 2...

<em><u>(47.50 x 2 = 95)</u></em>

<u>STEP 2: </u>So for $95, you will get 2 tons of rock!

Now to get the .5 tons of rock in price form, we have to get the price of the whole 2.5 tons and DIVIDE BY 2

<em><u>(47.50 ÷ 2 = 23.75)</u></em>

<u>STEP 3:</u> So now we have the costs for 2 tons and the price for HALF a ton.

What we do now is easy...we ADD THE VALUES TOGTHER!

<em><u>(95 + 23.75 = $118.75)</u></em>

The result of $118.75 after adding them together is the PRICE OF 2 TONS!

<u>I HOPE THIS HELPED YOU!</u>

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4 0
2 years ago
Which fractions are equivalent to 1/8+5/8? Check all that apply.
dolphi86 [110]
The equivalent fractions are 3/4 & 12/16 hope this helps!!
7 0
3 years ago
Read 2 more answers
Put the following equation in standard form and determine the quadratic, linear, and constant coefficients. -3x2 - 8 = 5x - 7
marusya05 [52]

Answer:

  • -3x² -5x -1 = 0
  • -3 (quadratic)
  • -5 (linear)
  • -1 (constant)

Step-by-step explanation:

The equation will be in standard form when terms are listed in order of decreasing degree, and the right side of the equation is 0.

<h3>Standard form</h3>

We can subtract the right-side expression from both sides to get standard form.

  -3x² -8 -(5x -7) = 5x -7 -(5x -7)

  -3x² -8 -5x +7 = 0 . . . . . . . simplify a bit

  -3x² -5x -1 = 0 . . . . . . . . . collect terms

The standard form equation can be written ...

  -3x² -5x -1 = 0

<h3>Coefficients</h3>

The quadratic coefficient is the coefficient of the term with degree 2. The quadratic coefficient is -3.

The linear coefficient is the coefficient of the term with degree 1. The linear coefficient is -5.

The constant coefficient is the coefficient of the term with no variables. The constant is -1.

__

<em>Additional comment</em>

We can make the leading coefficient positive by multiplying the equation by -1. This gives ...

  3x² +5x +1 = 0

with quadratic, linear, and constant coefficients 3, 5, 1.

This is a legitimate answer to this question. In the case of linear equations, the "standard form" has the constant on the right side of the equal sign, and the leading coefficient is required to be positive. A negative leading coefficient can sometimes lead to errors (when the sign is overlooked), so having a positive leading coefficient is often preferred.

8 0
2 years ago
What’s the Multiplicative inverse
mylen [45]
The multiplicative inverse of -1/3 is -3.

The product of a number and it’s multiplicative inverse equals 1.

So... -1/3 x -3/1 = 1

A negative times a negative equals a positive.


I hope this helped!
6 0
3 years ago
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