What is it? :DDDDDDDD
2 answers:
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Answer:
If we compare the p value and the significance level given and we can see that
so we can conclude that we have enough evidence to FAIL reject the null hypothesis, so we can't conclude that the true average speed is lower than 25 mph at 5% of signficance.
Step-by-step explanation:
Data given and notation
represent the sample mean
represent the sample standard deviation
sample size
represent the value that we want to test
represent the significance level for the hypothesis test.
t would represent the statistic (variable of interest)
represent the p value for the test (variable of interest)
State the null and alternative hypotheses.
We need to conduct a hypothesis in order to check if the true mean for the average speed is lower than 25 mph, the system of hypothesis would be:
Null hypothesis:
Alternative hypothesis:
If we analyze the size for the sample is < 30 and we don't know the population deviation so is better apply a t test to compare the actual mean to the reference value, and the statistic is given by:
(1)
Calculate the statistic
We can replace in formula (1) the info given like this:
P-value
The first step is calculate the degrees of freedom, on this case:
Since is a one side test the p value would be:
Conclusion
If we compare the p value and the significance level given and we can see that
so we can conclude that we have enough evidence to FAIL reject the null hypothesis, so we can't conclude that the true average speed is lower than 25 mph at 5% of signficance.
Answer:
The height of the tree is is 60m
Step-by-step explanation:
Let's answer a, as it is the only complete question.
We know that the angle of elevation of the top of a tree observed from a point 60m away, is 45°.
We can model this with a triangle rectangle, a sketch of it can be seen below (assuming that you are looking it from the ground).
You can see that the adjacent cathetus to the 45° angle is equal to 60m
And the opposite cathetus is the measure we want to find.
Now you can remember the trigonometric relation:
tan(a) = (opposite cathetus)/(adjacent cathetus).
So to find the height of the tree we need to solve:
tan(45°) = H/60m
This is just:
tan(45°)*60m = H =60m
The height of the tree is is 60m
