Answer:
D sentence 5
Step-by-step explanation:
Answer: ( -0.731, 0.682)
Step-by-step explanation:
The unit vector is defined as a vector that points in the same direction as our vector (137 degrees from the x-axis) and has a magnitude of 1.
Knowing the angle, is really simple to do it.
First, we know that for a radius R and an angle A, the rectangular coordinates can be written as:
x = R*cos(A)
y = R*sin(A)
And if we want that the magnitude/modulus of our vector to be 1, then R = 1, and we know that A = 137°
x = 1*cos(137°) = -0.731
y = 1*sin(137°) = 0.682
Then the unit vector is: ( -0.731, 0.682)
Answer:
71.123 mph ≤ μ ≤ 77.277 mph
Step-by-step explanation:
Taking into account that the speed of all cars traveling on this highway have a normal distribution and we can only know the mean and the standard deviation of the sample, the confidence interval for the mean is calculated as:
≤ μ ≤ 
Where m is the mean of the sample, s is the standard deviation of the sample, n is the size of the sample, μ is the mean speed of all cars, and
is the number for t-student distribution where a/2 is the amount of area in one tail and n-1 are the degrees of freedom.
the mean and the standard deviation of the sample are equal to 74.2 and 5.3083 respectively, the size of the sample is 10, the distribution t- student has 9 degrees of freedom and the value of a is 10%.
So, if we replace m by 74.2, s by 5.3083, n by 10 and
by 1.8331, we get that the 90% confidence interval for the mean speed is:
≤ μ ≤ 
74.2 - 3.077 ≤ μ ≤ 74.2 + 3.077
71.123 ≤ μ ≤ 77.277
70
7-0=7
81 or 18
8-1=7
92 or 29
9-2=7