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2 years ago

The perimeter of a shape is 25.71 cm calculate the value of the radius X takes pie to be 3.142

Mathematics

1 answer:

Mariulka [41]2 years ago

3 0

Answer:

5 cm

Step-by-step explanation:

Given a semicircle with perimeter 25.71 cm, we are required to find the radius of the circle.

Circumference of a Semicircle

=Length of the Circular part+Length of the diameter

$=\pi r+2r$

$If \: \pi=3.142, C=25.71\\Then:\\25.71=3.142r+2r\\r(3.142+2)=25.71\\5.142r=25.71\\r=25.71 \div5.142\\r=5cm$

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Rewrite using a single positive exponent 5^6/5^4

Sindrei [870]

Answer:

Step-by-step explanation:

We can divide exponents by subtract 4 from 6. So, now we have 5^2 or 25.

The other way to solve to check our answer is to do the math.

5^6 = 15625

5^4 = 625

15625/625 = 25

So, we know we have the correct answer.

5 0

3 years ago

Is 2.356... rational or irrational

777dan777 [17]

Answer:

Rational

Step-by-step explanation:

6 0

3 years ago

Read 2 more answers

Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.â Suppose a small group of 11 Allen's humming

alexira [117]

Answer:

$3.15-1.28\frac{0.38}{\sqrt{11}}=3.003$

$3.15+ 1.28\frac{0.38}{\sqrt{11}}=3.297$

So on this case the 80% confidence interval would be given by (3.003;3.297)

And the margin of error is given by:

$ME = 1.28\frac{0.38}{\sqrt{11}}= 0.147$

Step-by-step explanation:

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".

$\bar X=3.15$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=0.38$ represent the population standard deviation

n=11 represent the sample size

Solution to the problem

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

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.80 or 80%, the value of $\alpha=0.2$ and $\alpha/2 =0.1$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NOR.INV(0.1,0,1)".And we see that $z_{\alpha/2}=1.28$

Now we have everything in order to replace into formula (1):

$3.15-1.28\frac{0.38}{\sqrt{11}}=3.003$

$3.15+ 1.28\frac{0.38}{\sqrt{11}}=3.297$

So on this case the 80% confidence interval would be given by (3.003;3.297)

And the margin of error is given by:

$ME = 1.28\frac{0.38}{\sqrt{11}}= 0.147$

8 0

3 years ago

A student who is trying to write a paper for a course has a choice of two topics, A and B. If topic A is chosen, the student wil

algol13

Answer:

P(Topic A) = 0.91

P(Topic B) = 0.9163

The student should choose Topic B to maximize the probability of writing a good paper because P(Topic B)>P(Topic A).

Step-by-step explanation:

If Topic A is chosen, 2 books will be ordered (n=2)

If topic B is chosen, 4 books will be ordered (n=4)

Probability that a book arrives in time (p) = 0.7

Probability that a book does not arrive in time (q) = 1 - p = 1 - 0.7 = 0.3

We will <u>use the binomial distribution</u> to find out which topic should the student choose to maximize the probability of writing a good paper. The binomial distribution formula is:

P(X=x) = ⁿCˣ pˣ qⁿ⁻ˣ

where p = probability of success

q = probability of failure

n = total no. of trials

x = no. of successful trials

For Topic A, n = 2, p=0.7 and q=0.3. If topic A is chosen, the student will use at least half the books i.e. he will use either 1 or 2 books. So,

P(Topic A) = P(X=1) + P(X=2)

=²C₁ (0.7)¹(0.3)²⁻¹ + ²C₂ (0.7)²(0.3)²⁻²

= 0.42 + 0.49

P(Topic A) = 0.91

For topic B, n=4, p=0.7 and q=0.3. If topic B is chosen, the student will choose 2 or more books i.e. 2, 3 or 4 books.

P(Topic B) = P(X=2) + P(X=3) + P(X=4)

= ⁴C₂ (0.7)²(0.3)⁴⁻² + ⁴C₃ (0.7)³(0.3)⁴⁻³ + ⁴C₄ (0.7)⁴(0.3)⁴⁻⁴

= 0.2646 + 0.4116 + 0.2401

P(Topic B) = 0.9163

The student should choose Topic B to maximize the probability of writing a good paper because P(Topic B)>P(Topic A) as calculated above.

3 0

3 years ago

Help me …… please ! I Just need help

frozen [14]

Answer:

(2,-2)

Step-by-step explanation:

y=-4x+6

y=3x-8

plug the y's in for each other to get:

-4x+6=3x-8 <----- solve from there

+8 +8

-4x+14=3x

+4x +4x

14=7x

/7 /7

x=2

now plug the x in to get y (in any problem)

y=3(2)-8

y=6-8

y=-2

7 0

3 years ago