Answer:
Option (3)
Step-by-step explanation:
By applying cosine rule in the triangle ABC,
BC² = AC² + AB² - 2(AC)(AB)cosA
5² = 3² + 7²- 2(3)(7)cosA
25 = 9 + 49 - 42cos(A)
25 = 58 - 42cos(A)
cos(A) =
A =
A = 38.21°
A ≈ 38°
Option (3) will be the correct option.
Using the t-distribution, it is found that the p-value of the test is 0.007.
At the null hypothesis, it is <u>tested if the mean lifetime is not greater than 220,000 miles</u>, that is:
At the alternative hypothesis, it is <u>tested if the mean lifetime is greater than 220,000 miles</u>, that is:
.
We have the <u>standard deviation for the sample</u>, thus, the t-distribution is used. The test statistic is given by:
The parameters are:
For this problem:
Then, the value of the test statistic is:
We have a right-tailed test(test if the mean is greater than a value), with <u>t = 2.69</u> and 23 - 1 = <u>22 df.</u>
Using a t-distribution calculator, the p-value of the test is of 0.007.
A similar problem is given at brainly.com/question/13873630