Answer:
Kevin needs 96 points on his last test to raise his mean test score to 90 points.
Step-by-step explanation:
we know that
The mean score is the total of all scores divided by the total number of tests.
Let
x_1 ----> the score in the first math test
x_2 ----> the score in the second math test
x_3 ----> the score in the third math test
x_4 ----> the score in the fourth math test
we have
After taking the first 3 tests, his mean test score is 88 points
so
----> equation A
How many points does he need on his last test to raise his mean test score to 90 points?
so
----> equation B
substitute equation A in equation B
solve for x_4
Therefore
Kevin needs 96 points on his last test to raise his mean test score to 90 points.
Answer: whats the question?
Step-by-step explanation:
Answer:
(1/2, 1)
2
Step-by-step explanation:
x² + y² − x − 2y − 11/4 = 0
x² − x + y² − 2y = 11/4
Complete the squares.
x² − x + 1/4 + y² − 2y + 1 = 11/4 + 1/4 + 1
(x − 1/2)² + (y − 1)² = 4
The center of the circle is (1/2, 1) and the radius of the circle is 2.
121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range
The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:
So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range
That's probably the answer they're looking for.
