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statuscvo [17]
3 years ago
13

The circumference of a circle is 18.84 meters. what is the circles area

Mathematics
1 answer:
Fed [463]3 years ago
5 0
The area is about 28.25m²
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"Eighty and fifteen hundredths" in numbers<br>(decimals)
Black_prince [1.1K]

Answer:

80.15

Step-by-step explanation:

Eighty and fifteen hundredths = 80.15

4 0
3 years ago
How to finsd the set of numbers if the mean, median and mode is given
Bad White [126]

Answer:

a) we have the numbers 0, 2, 3, 5, 5. The mean and the median are both 3

b) we have the numbers 0, 0, 3, 5, 7. The mean and the median are both 3

In both cases the mean and the median are 3, but the mode differs. The mean and the median do not uniquely determine the mode.

Step-by-step explanation:

3 0
2 years ago
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A doctor released the results of clinical trials for a vaccine to prevent a particular disease. In these clinical​ trials, 200,0
CaHeK987 [17]

Answer:

1) No, there is  not  enough evidence to support the claim that the vaccine was effective (P-value=0.104) .

The null and alternative hypothesis are:

H_0: \pi_1-\pi_2=0\\\\H_a:\pi_1-\pi_2< 0

being the subindex 1 for the experimental group and subindex 2 for the control group.

2) Test statistic z=-1.26

Step-by-step explanation:

This is a hypothesis test for the difference between proportions.

The claim is that the vaccine was effective.

Then, the null and alternative hypothesis are:

H_0: \pi_1-\pi_2=0\\\\H_a:\pi_1-\pi_2< 0

The significance level is 0.01.

The sample 1 (experimental group), of size n1=100000 has a proportion of p1=0.0002.

p_1=X_1/n_1=21/100000=0.0002

The sample 2 (control group), of size n2=100000 has a proportion of p2=0.0003.

p_2=X_2/n_2=30/100000=0.0003

The difference between proportions is (p1-p2)=-0.0001.

p_d=p_1-p_2=0.0002-0.0003=-0.0001

The pooled proportion, needed to calculate the standard error, is:

p=\dfrac{X_1+X_2}{n_1+n_2}=\dfrac{21+30}{100000+100000}=\dfrac{51}{200000}=0.00026

The estimated standard error of the difference between means is computed using the formula:

s_{p1-p2}=\sqrt{\dfrac{p(1-p)}{n_1}+\dfrac{p(1-p)}{n_2}}=\sqrt{\dfrac{0.00026*0.99974}{100000}+\dfrac{0.00026*0.99974}{100000}}\\\\\\s_{p1-p2}=\sqrt{0+0.0000000025}=\sqrt{0.0000000051}=0.000071

Then, we can calculate the z-statistic as:

z=\dfrac{p_d-(\pi_1-\pi_2)}{s_{p1-p2}}=\dfrac{-0.00009-0}{0.000071}=\dfrac{-0.00009}{0.000071}=-1.26

This test is a left-tailed test, so the P-value for this test is calculated as (using a z-table):

P-value=P(z

As the P-value (0.104) is bigger than the significance level (0.01), the effect is not significant.

The null hypothesis failed to be rejected.

There is  not  enough evidence to support the claim that the vaccine was effective.

6 0
2 years ago
Factor: (a+3)^2 -a(a+3)
lutik1710 [3]

Answer:

3(a +3)

Step-by-step explanation:

(a+3)^2 -a(a+3)

FOIL

a^2 +3a+3a+9 -a(a+3)

Distribute

a^2 +3a +3a +9 -a^2 -3a

Combine like terms

3a +9

FACTOR out a+3

(a+3)( a+3 -a)

(a+3) (3)

3(a+3)

6 0
2 years ago
Read 2 more answers
If the directrix of a parabola is the horizontal line y = 3, what is true of the parabola?
12345 [234]
The correct answer is b), or x² = -12y.

Explanation:
This equation may be written in standard form as
y=- \frac{1}{12} x^{2}
The coefficient in front of x² is negative so the curve is downward.
The vertex has coordinates (0,0).
The vertex is equidistant from the directrix and the focus, so the focus is (0, -3).

3 0
3 years ago
Read 2 more answers
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