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1 year ago

Radius of a semi circle

Mathematics

2 answers:

Ivahew [28]1 year ago

8 0

The area for semi circle is: (pi)(r^2)/2

A= 3.142 x (8.2)^2 / 2

A= 110.8 cm^2

bulgar [2K]1 year ago

6 0

A=3.142*r^2
Area of the circle= 3.142*8.2^2
=211.26
Because it’s a semicircle, divide by two.
211.26/2 = 105.6

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Help me please (no links please)

stich3 [128]

a) This part is already complete I think..

b) This is a cuboid and lateral surface area of cuboid is: 2(lb +bh + hl)

= 2( 10 × 3 + 3 × 7 + 7 × 10)

= 2(30 + 21 + 70)

= 2 × 121 = 242 cm²

Now, the area of top & bottom: lb

= 2 × 10 × 3

= 60 cm²

Neglecting the top & bottom surface area of cuboid:

= 242 - 60

= 180 cm²

c) The total surface area us 242.. I have already done that part above...

__________________________

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2 years ago

Solve the following recurrence relation: <br> <img src="https://tex.z-dn.net/?f=A_%7Bn%7D%3Da_%7Bn-1%7D%2Bn%3B%20a_%7B1%7D%20%3D

-Dominant- [34]

By iteratively substituting, we have

$a_n = a_{n-1} + n$

$a_{n-1} = a_{n-2} + (n - 1) \implies a_n = a_{n-2} + n + (n - 1)$

$a_{n-2} = a_{n-3} + (n - 2) \implies a_n = a_{n-3} + n + (n - 1) + (n - 2)$

and the pattern continues down to the first term $a_1=0$ ,

$a_n = a_{n - (n - 1)} + n + (n - 1) + (n - 2) + \cdots + (n - (n - 2))$

$\implies a_n = a_1 + \displaystyle \sum_{k=0}^{n-2} (n - k)$

$\implies a_n = \displaystyle n \sum_{k=0}^{n-2} 1 - \sum_{k=0}^{n-2} k$

Recall the formulas

$\displaystyle \sum_{n=1}^N 1 = N$

$\displaystyle \sum_{n=1}^N n = \frac{N(N+1)}2$

It follows that

$a_n = n (n - 2) - \dfrac{(n-2)(n-1)}2$

$\implies a_n = \dfrac12 n^2 + \dfrac12 n - 1$

$\implies \boxed{a_n = \dfrac{(n+2)(n-1)}2}$

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2 years ago

17% of what number is 3.4

saw5 [17]

Answer:

Step-by-step explanation:

We already have our first value 3.4 and the second value 17. Let's assume the unknown value is Y which answer we will find out.

As we have all the required values we need, Now we can put them in a simple mathematical formula as below:

Step 1 ---> 3.4 = 17% × Y

Step 2 ---> 3.4 = 17/100 × Y

Multiplying both sides by 100 and dividing both sides of the equation by 17 we will arrive at:

Step 3 ---> Y = 3.4 × 100/17

Step 4 ---> Y = 3.4 × 100 ÷ 17

Step 5 ---> Y = 20

Finally, we have found the value of Y which is 20 and that is our answer.

<h3><u>*You can easily calculate 3.4 is 17 percent of what number by using any regular calculator, simply enter 3.4 × 100 ÷ 17 and you will get your answer which is 20*</u></h3>

4 0

2 years ago

3x + 9 > -18

aleksklad [387]

Answer:

The written form would be "Nine more than three times a number is greater than -18.

Step-by-step explanation:

To graph it, you must first solve for x.

3x + 9 > -18

3x > -27

x > -9

Now we can graph this by putting an open dot at -9 and then drawing an arrow to the right.

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2 years ago

An environmentalist wants to find out the fraction of oil tankers that have spills each month. Step 2 of 2 : Suppose a sample of

rewona [7]

Answer:

The 80% confidence interval for the population proportion of oil tankers that have spills each month is (0.199, 0.257).

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

Suppose a sample of 333 tankers is drawn. Of these ships, 257 did not have spills.

333 - 257 = 76 have spills.

This means that $n = 333, \pi = \frac{76}{333} = 0.228$

80% confidence level

So $\alpha = 0.2$ , z is the value of Z that has a pvalue of $1 - \frac{0.2}{2} = 0.9$ , so $Z = 1.28$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.228 - 1.28\sqrt{\frac{0.228*0.772}{333}} = 0.199$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.228 + 1.28\sqrt{\frac{0.228*0.772}{333}} = 0.257$

The 80% confidence interval for the population proportion of oil tankers that have spills each month is (0.199, 0.257).

6 0

2 years ago