Performing a study on the development of body height, a student randomly measures the height of 30 persons in country A. The results turn out to be: {1.7, 1.6, 1.8, 1.9, 1.75, 1.83, 1.82, 1.65, 1.95, 1.69, 1.82, 1.87, 1.65, 1.54, 1.98, 1.78, 1.69, 1.75, 1.62, 1.64, 1.75, 1.8, 1.65, 1.7, 1.82, 1.62, 1.83, 1.75, 1.7, 1.65}. In the literature, a result is found that 10 years before, the average height of persons in country A was determined to be 1.73 and standard deviation is 0.2 .

Given that the acceptable threshold for significance is 5%, can this data be used to show that the average height of individuals in country A has increased in the last 10 years?
(Show your calculations).

Respuesta :

Answer:

[tex] t= \frac{1.743-1.73}{\frac{0.107}{\sqrt{30}}}= 0.665[/tex]

[tex] df = n-1= 30-1=29[/tex]

[tex] p_v= P(t_{29}>1.73)= 0.047[/tex]

And if we compare the p value obtained and the significance level provided of 0.05 or 5% we see that [tex]p_v<\alpha[/tex] so then we have enough evidence to conclude that the true mean for this case is significantly higher tha 1.73 since we reject the null hypothesis for the test

Step-by-step explanation:

We have the following dataset given:

1.7, 1.6, 1.8, 1.9, 1.75, 1.83, 1.82, 1.65, 1.95, 1.69, 1.82, 1.87, 1.65, 1.54, 1.98, 1.78, 1.69, 1.75, 1.62, 1.64, 1.75, 1.8, 1.65, 1.7, 1.82, 1.62, 1.83, 1.75, 1.7, 1.65

We can calculate the sample mean and deviation from this data with the following formulas:

[tex]\bar X =\frac{\sum_{i=1}^n X_i}{n}[/tex]

[tex]s =\sqrt{\frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}}[/tex]

And replacing we got:

[tex]\bar X= 1.743 ,s=0.107 , n=30[/tex]

From previous info we know that 10 years before, the average height of persons in country A was determined to be 1.73 and standard deviation is 0.2.

We can use a one t test in order to check the claim that he average height of individuals in country A has increased in the last 10 years

Null hypothesis: [tex]\mu \leq 1.73[/tex]

Alternative hypothesis: [tex]\mu>1.73[/tex]

The statistic is given by:

[tex] t=\frac{\bar X \mu}{\frac{s}{\sqrt{n}}}[/tex]

Replacing the info given we got:

[tex] t= \frac{1.743-1.73}{\frac{0.107}{\sqrt{30}}}= 0.665[/tex]

The degrees of freedom for this test are given by:

[tex] df = n-1= 30-1=29[/tex]

Now we can calculate the p value with the following probability:

[tex] p_v= P(t_{29}>1.73)= 0.047[/tex]

And if we compare the p value obtained and the significance level provided of 0.05 or 5% we see that [tex]p_v<\alpha[/tex] so then we have enough evidence to conclude that the true mean for this case is significantly higher tha 1.73 since we reject the null hypothesis for the test