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allochka39001 [22]
3 years ago
8

In a hall, there are 75 chairs. Out of these 60% are plastic and 40% are metal. Find the number of chairs of each type ?

Mathematics
2 answers:
Ivahew [28]3 years ago
8 0
Plastic=45 metal =30
poizon [28]3 years ago
4 0

Answer:

plastic = 45

metal = 30

Step-by-step explanation:

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In the figure is a right triangle ABC with AC=10cm and BC=6cm. Determine: 1.5.1 The height AB (hint: Theorem of Pythagoras)
Alexxandr [17]

Answer:

height AB is 8 cm

Step-by-step explanation:

AB= √AC^2- BC^2

= √(10)^2- (6)^2

= √100-36

= √64

= 8

3 0
3 years ago
The following data were collected from 12 rain gauges in a park. Build a 95% CI for the mean rainfall at the park.
dybincka [34]

Answer:

Critical values:t_{\alpha/2}=-2.201 t_{1-\alpha/2}=2.201

95% confidence interval would be given by (3.646;4.472)

Step-by-step explanation:

1) Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The data is:

4.65 3.89 2.73 4.35 3.80 4.86 4.33 4.37 4.76 4.05 3.05 3.87

2) Compute the sample mean and sample standard deviation.

In order to calculate the mean and the sample deviation we need to have on mind the following formulas:  

\bar X= \sum_{i=1}^n \frac{x_i}{n}

s=\sqrt{\frac{\sum_{i=1}^n (x_i-\bar X)}{n-1}}

=AVERAGE(4.65,3.89,2.73, 4.35, 3.8, 4.86, 4.33, 4.37, 4.76, 4.05, 3.05, 3.87)

On this case the average is \bar X= 4.059

=STDEV.S(4.65,3.89,2.73, 4.35, 3.8, 4.86, 4.33, 4.37, 4.76, 4.05, 3.05, 3.87)

The sample standard deviation obtained was s=0.6503

3) Find the critical value t* Use the formula for a CI to find upper and lower endpoints

In order to find the critical value we need to take in count that our sample size n =12 <30 and on this case we don't know about the population standard deviation, so on this case we need to use the t distribution. Since our interval is at 95% of confidence, our significance level would be given by \alpha=1-0.95=0.05 and \alpha/2 =0.025. The degrees of freedom are given by:

df=n-1=12-1=11

We can find the critical values in excel using the following formulas:

"=T.INV(0.025,11)" for t_{\alpha/2}=-2.201

"=T.INV(1-0.025,11)" for t_{1-\alpha/2}=2.201

The confidence interval for the mean is given by the following formula:

\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}  

And we can use Excel to calculate the limits for the interval

Lower interval : "=4.059 -2.201*(0.6503/SQRT(12))" =3.646

Upper interval :  "=4.059 +2.201*(0.6503/SQRT(12))" =4.472

So the 95% confidence interval would be given by (3.646;4.472)

8 0
3 years ago
Please help i will give brainliest
RideAnS [48]
The answer would be C because it’s the only fraction that does not equal 0.4
8 0
3 years ago
Compare the triangles and determine whether they can be proven congruent by SSS, SAS, ASA, AAS, or HL. If not, type "NONE".
EleoNora [17]

Answer: HL

Step-by-step explanation:

The hypotenuse is actually a shared side of the two triangles. (The line segment that crosses the middle of the rectangle) The hypotenuse is the side of a triangle opposite the 90 degree angle. We can use this for hypotenuse congruency. The diagram also shows the shorter legs of the two triangles are congruent. (The legs refer to the sides that make the 90 degree angle)

So we have hypotenuse congruency and leg congruency.

=HL

6 0
2 years ago
Shawn is typing a paper for class he can type 1 7/11 pages in 1/3 of an hour how many pages can he read in one hour
tatuchka [14]

Answer:

Step-by-step explanation:

1/3 of an hour is 1/3 × 60 minutes = 20 minutes.

no of pages for 1 hour = 3 × 18/11

54

----    =     4    9

                    ------

11                     11

hope this help :P

4 0
2 years ago
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