Answer:
![t_(calc)= \pm 1.576](https://img.qammunity.org/2021/formulas/mathematics/college/62bgeje8nby4770rjt0xg80nv3hz05w4z0.png)
Now we need to find the p value , we need to take in count that we are conducting a bilateral test so then the p value can be calculated with this probability:
![p_v = 2*P(t_(21)<-1.576) =0.12997](https://img.qammunity.org/2021/formulas/mathematics/college/vvmmu8mxbmw5w6fl7x1z0ty30jwenudmrb.png)
And we can find this p value with the following excel formula for example:
"=2*(T.DIST(-1.576,21,TRUE))"
Explanation:
For this case they want to conduct a test in order to check if the true mean for the smartphone carrier's data speeds is equal to 17 Mbps, so then the system of hypothesis are:
Null hypothesis:
![\mu = 17](https://img.qammunity.org/2021/formulas/mathematics/college/64p3bklsbeae274ihooxxt4qy4rtz4s2zn.png)
Alternative hypothesis:
![\mu \\eq 17](https://img.qammunity.org/2021/formulas/mathematics/college/qpj6tnh481s9va7i1aytalzf1tkaf2vniz.png)
The statistic to check this hypothesis is:
![t= (\bar X -\mu)/((s)/(√(n)))](https://img.qammunity.org/2021/formulas/mathematics/college/gw5b6h1rdiddhnoonemrwi385utzik1zn7.png)
Since we don't know the true population deviation. We know that the sample size is equal to n =22, so then we can find the degrees of freedom given by this formula:
![df = n-1 = 22-1=21](https://img.qammunity.org/2021/formulas/mathematics/college/lp68v8q9160qz6kqlfniizjj5ljry7pmum.png)
After replace in the statistic formula we have the statistic provided:
![t_(calc)= \pm 1.576](https://img.qammunity.org/2021/formulas/mathematics/college/62bgeje8nby4770rjt0xg80nv3hz05w4z0.png)
Now we need to find the p value , we need to take in count that we are conducting a bilateral test so then the p value can be calculated with this probability:
![p_v = 2*P(t_(21)<-1.576) =0.12997](https://img.qammunity.org/2021/formulas/mathematics/college/vvmmu8mxbmw5w6fl7x1z0ty30jwenudmrb.png)
And we can find this p value with the following excel formula for example:
"=2*(T.DIST(-1.576,21,TRUE))"