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3 years ago

The area of circle is 770cm^2then find its circumfrence

Mathematics

1 answer:

Gala2k [10]3 years ago

6 0

Answer:

The circumference is 98.39 centimeters (rounded to 2 decimal places)

Step-by-step explanation:

The area of a circle has the formula $\pi r^2$

The circumference of a circle has the formula $2\pi r$

First, let's find r from area given:

$\pi r^ 2= 770\\r^2 = \frac{770}{\pi}\\r=\sqrt{\frac{770}{\pi}} \\r=15.66$

Now, we can use this value of r and plug in into the formula for circumference. Shown below:

$2\pi (15.66)\\=98.39$

The circumference is 98.39 centimeters (rounded to 2 decimal places)

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The mean cost of domestic airfares in the United States rose to an all-time high of $385 per ticket (Bureau of Transportation St

saveliy_v [14]

Answer:

a)0.067

b)0.111

c)0.612

d)$687.28

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = $385

Standard Deviation, σ = $110

We are given that the distribution of domestic airfares is a bell shaped distribution that is a normal distribution.

Formula:

$z_{score} = \displaystyle\frac{x-\mu}{\sigma}$

a) P(domestic airfare is $550 or more)

P(x > 550)

$P( x > 550) = P( z > \displaystyle\frac{550 - 385}{110}) = P(z > 1.5)$

$= 1 - P(z \leq 1.5)$

Calculation the value from standard normal z table, we have,

$P(x > 550) = 1 - 0.933 = 0.067= 6.7\%$

b) P(domestic airfare is $250 or less)

$P(x \leq 250) = P(z \leq \displaystyle\frac{250-385}{110}) = P(z \leq -1.22)$

Calculating the value from the standard normal table we have,

$P( x \leq 250) = 0.111 = 11.1\%$

c))P(domestic airfare is between $300 and $500)

$P(300 \leq x \leq 500) = P(\displaystyle\frac{300 - 385}{110} \leq z \leq \displaystyle\frac{500-385}{110}) = P(-0.77 \leq z \leq 1.04)\\\\= P(z \leq 1.04) - P(z < -0.77)\\= 0.851 - 0.239 = 0.612 = 61.2\%$

$P(300 \leq x \leq 500) = 61.2\%$

d) P(X=x) = 0.03

We have to find the value of x such that the probability is 0.03.

P(X > x)

$P( X > x) = P( z > \displaystyle\frac{x - 385}{110})=0.03$

$= 1 -P( z \leq \displaystyle\frac{x - 385}{110})=0.03$

$=P( z \leq \displaystyle\frac{x - 385}{110})=0.997$

Calculation the value from standard normal z table, we have,

$\displaystyle\frac{x - 385}{110} = 2.748\\x = 687.28$

Hence, the domestic fares must be $687.28 or greater for them to lie in the highest 3%.

7 0

3 years ago

Pat created a scatter plot and drew a line of best fit, as shown.

Hunter-Best [27]

<h3>Answer: Choice D</h3><h3>y = (-1/5)x + 7</h3>

======================================

Work Shown:

We will only focus on the two points that are on the regression line.

Those two points are (10,5) and (15,4)

Let (x1,y1) = (10,5) and (x2,y2) = (15,4)

Find the slope of the line through (x1,y1) = (10,5) and (x2,y2) = (15,4)

m = (y2 - y1)/(x2 - x1)

m = (4 - 5)/(15 - 10)

m = -1/5

m = -0.2

Plug m = -0.2, and (x1,y1) = (10,5) into the point slope formula. Solve for y

y - y1 = m(x - x1)

y - 5 = -0.2(x - 10)

y - 5 = -0.2*x - 0.2*(-10) ... distribute

y - 5 = -0.2*x + 2

y - 5+5 = -0.2*x + 2 + 5 ... add 5 to both sides

y = -0.2*x + 7

y = (-1/5)*x + 7 .... convert -0.2 to -1/5

The equation y = (-1/5)x + 7 is in the form y = mx+b with m = -1/5 = -0.2 as the slope and b = 7 as the y intercept. The y intercept is where the graph crosses the vertical y axis. More specifically, the location of the y intercept in this case is at the point (0,7).

4 0

3 years ago

To save money, a local charity organization wants to target its mailing requests for donations to individuals who are most suppo

mars1129 [50]

Answer:

The 80% confidence interval for difference between two means is (0.85, 1.55).

Step-by-step explanation:

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

$CI=(\bar x_{1}-\bar x_{2})\pm t_{\alpha/2,(n_{1}+n_{2}-2)}\times SE_{\bar x_{1}-\bar x_{2}}$