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Alenkasestr [34]
3 years ago
12

Three circles are arranged in a row so that each is tangent to the

Mathematics
1 answer:
lorasvet [3.4K]3 years ago
7 0
<span>πd is the circumference of a circle, so with a diameter of 4 a single circle has a circumference of 4π. 1/3 of each circle is in contact with the belt, so that total part is still 4π. Then, the part of the belt connecting from tangent to tangent is 2 radii, so 3 areas is 12. The belt would then be 12+4π cm.</span>
You might be interested in
How to do this question plz answer me step by step plzz plz ​
Firdavs [7]

Answer:

24.99 cm

Step-by-step explanation:

We are provided with the radius of the circle so we can use that to solve for the circumference(perimeter) of the circle. The formula to solve for the circumference is 2*pi*r.

2*pi*7 = 14pi = 43.98 cm

Although this is the circumference of the entire circle... To solve for the circumference of a quarter-circle we must find the quarter of that:

43.98 * 1/4 = 10.99 cm

We are already provided with the other two sides, which are both equal to 7 cm since they are radii.

Perimeter = 10.99 +7 + 7 = 24.99 cm

Hope this helps!

8 0
3 years ago
A Government company claims that an average light bulb lasts 270 days. A researcher randomly selects 18 bulbs for testing. The s
Fofino [41]

Answer:

31.92% probability that 18 randomly selected bulbs would have an average life of no more than 260 days

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution

When the distribution is normal, we use the z-score formula.

In a set with mean \mu and standard deviation \sigma, the zscore of a measure X is given by:

Z = \frac{X - \mu}{\sigma}

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean \mu and standard deviation \sigma, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean \mu and standard deviation s = \frac{\sigma}{\sqrt{n}}.

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean \mu = p and standard deviation s = \sqrt{\frac{p(1-p)}{n}}

In this question, we have that:

\mu = 270, \sigma = 90, n = 18, s = \frac{90}{\sqrt{18}} = 21.2

What is the probability that 18 randomly selected bulbs would have an average life of no more than 260 days?

This is the pvalue of Z when X = 260. So

Z = \frac{X - \mu}{\sigma}

By the Central Limit Theorem

Z = \frac{X - \mu}{s}

Z = \frac{260 - 270}{21.2}

Z = -0.47

Z = -0.47 has a pvalue of 0.3192.

31.92% probability that 18 randomly selected bulbs would have an average life of no more than 260 days

5 0
3 years ago
Determine the mean of the following data. Choose the correct option.<br> 7, 8, 9, 2, 4, 5, 12, 9
Brut [27]

Answer:

7

Step-by-step explanation:

mean means average

there are 8 numbers

add them all up

7+8+9+2+4+5+12+9=56

divide 56 by 8 = 7

8 0
2 years ago
PLEASE HELP..MATH 8TH GRADE​
jolli1 [7]

Answer. z = ± √10 = ± 3.1623

8 0
3 years ago
Read 2 more answers
What is the answer to this question?
Anni [7]
Three is also 44 and two and four are 136
7 0
3 years ago
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