Answer:
circumference=50.24 cm
area=200.96 cm²
Step-by-step explanation:
r=16/2=8
circumference=2πr=2×3.14×8=50.24 cm
area=πr^2=3.14×8²=200.96 cm²
I know the The leading coefficient is 4
Answer:
a
The null hypothesis is
![H_o : \mu = 21](https://tex.z-dn.net/?f=H_o%20%20%3A%20%5Cmu%20%20%3D%20%2021)
The Alternative hypothesis is
![H_a : \mu< 21](https://tex.z-dn.net/?f=H_a%20%20%3A%20%20%5Cmu%3C%20%20%2021)
b
![\sigma_{\= x} = 0.8944](https://tex.z-dn.net/?f=%5Csigma_%7B%5C%3D%20x%7D%20%3D%20%20%200.8944)
c
![t = -2.236](https://tex.z-dn.net/?f=t%20%3D%20-2.236)
d
Yes the mean population is significantly less than 21.
Step-by-step explanation:
From the question we are given
a set of data
20 18 17 22 18
The confidence level is 90%
The sample size is n = 5
Generally the mean of the sample is mathematically evaluated as
![\= x = \frac{20 + 18 + 17 + 22 + 18}{5}](https://tex.z-dn.net/?f=%5C%3D%20x%20%20%3D%20%20%5Cfrac%7B20%20%2B%2018%20%2B%20%2017%20%2B%20%2022%20%2B%20%2018%7D%7B5%7D)
![\= x = 19](https://tex.z-dn.net/?f=%5C%3D%20x%20%20%3D%20%2019)
The standard deviation is evaluated as
![\sigma = \sqrt{ \frac{\sum (x_i - \= x)^2}{n} }](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%20%5Csqrt%7B%20%5Cfrac%7B%5Csum%20%28x_i%20-%20%5C%3D%20x%29%5E2%7D%7Bn%7D%20%7D)
![\sigma = \sqrt{ \frac{ ( 20- 19 )^2 + ( 18- 19 )^2 +( 17- 19 )^2 +( 22- 19 )^2 +( 18- 19 )^2 }{5} }](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%20%5Csqrt%7B%20%5Cfrac%7B%20%28%2020-%2019%20%29%5E2%20%2B%20%28%2018-%2019%20%29%5E2%20%2B%28%2017-%2019%20%29%5E2%20%2B%28%2022-%2019%20%29%5E2%20%2B%28%2018-%2019%20%29%5E2%20%7D%7B5%7D%20%7D)
![\sigma = 2](https://tex.z-dn.net/?f=%5Csigma%20%3D%202)
Now the confidence level is given as 90 % hence the level of significance can be evaluated as
![\alpha = 100 - 90](https://tex.z-dn.net/?f=%5Calpha%20%3D%20100%20-%2090)
%
![\alpha =0.10](https://tex.z-dn.net/?f=%5Calpha%20%3D0.10)
Now the null hypothesis is
![H_o : \mu = 21](https://tex.z-dn.net/?f=H_o%20%20%3A%20%5Cmu%20%20%3D%20%2021)
the Alternative hypothesis is
![H_a : \mu< 21](https://tex.z-dn.net/?f=H_a%20%20%3A%20%20%5Cmu%3C%20%20%2021)
The standard error of mean is mathematically evaluated as
![\sigma_{\= x} = \frac{\sigma}{ \sqrt{n} }](https://tex.z-dn.net/?f=%5Csigma_%7B%5C%3D%20x%7D%20%3D%20%20%20%5Cfrac%7B%5Csigma%7D%7B%20%5Csqrt%7Bn%7D%20%7D)
substituting values
![\sigma_{\= x} = \frac{2}{ \sqrt{5 } }](https://tex.z-dn.net/?f=%5Csigma_%7B%5C%3D%20x%7D%20%3D%20%20%20%5Cfrac%7B2%7D%7B%20%5Csqrt%7B5%20%7D%20%7D)
![\sigma_{\= x} = 0.8944](https://tex.z-dn.net/?f=%5Csigma_%7B%5C%3D%20x%7D%20%3D%20%20%200.8944)
The test statistic is evaluated as
![t = \frac{\= x - \mu }{ \frac{\sigma }{\sqrt{n} } }](https://tex.z-dn.net/?f=t%20%3D%20%20%5Cfrac%7B%5C%3D%20x%20-%20%5Cmu%20%7D%7B%20%5Cfrac%7B%5Csigma%20%7D%7B%5Csqrt%7Bn%7D%20%7D%20%7D)
substituting values
![t = \frac{ 19 - 21 }{ 0.8944 }](https://tex.z-dn.net/?f=t%20%3D%20%20%5Cfrac%7B%2019%20%20-%2021%20%7D%7B%200.8944%20%7D)
![t = -2.236](https://tex.z-dn.net/?f=t%20%3D%20-2.236)
The critical value of the level of significance is obtained from the critical value table for z values as
![z_{0.10} = 1.28](https://tex.z-dn.net/?f=z_%7B0.10%7D%20%3D%20%201.28)
Looking at the obtained value we see that
is greater than the test statistics value so the null hypothesis is rejected
<h3>
Answer: -0.81</h3>
Work Shown:
z = (x - mu)/sigma
z = (71 - 74)/(3.7)
z = -0.8108 approximately
z = -0.81