Answer:
The interpretation is that we are 90% sure that the true average salary of the district is in this interval.
Step-by-step explanation:
x% confidence interval:
A confidence interval is built from a sample, has bounds a and b, and has a confidence level of x%. It means that we are x% confident that the population mean is between a and b.
In this question:
The 90% confidence interval for the average salary of the district is [41500,49750].
This means that we are 90% sure that the true average salary of the district is in this interval.
Answer:
3rd option
Step-by-step explanation:
A direct variation is expressed in this form:
y = kx
1. y - 4x = 8
y = 4x + 8 is not a direct variation
2. y + 2 = 7x
y = 7x - 2 is not a direct variation
3. y - 3x = 0
y = 3x is a direct variation
4. y = 5x - 2
y = 5x - 2 is not direct variation
Answer:
Step-by-step explanation:
Answer:
<h2>14mph</h2>
Step-by-step explanation:
Given the gas mileage for a certain vehicle modeled by the equation m=−0.05x²+3.5x−49 where x is the speed of the vehicle in mph. In order to determine the speed(s) at which the car gets 9 mpg, we will substitute the value of m = 9 into the modeled equation and calculate x as shown;
m = −0.05x²+3.5x−49
when m= 9
9 = −0.05x²+3.5x−49
−0.05x²+3.5x−49 = 9
0.05x²-3.5x+49 = -9
Multiplying through by 100
5x²+350x−4900 = 900
Dividing through by 5;
x²+70x−980 = 180
x²+70x−980 - 180 = 0
x²+70x−1160 = 0
Using the general formula to get x;
a = 1, b = 70, c = -1160
x = -70±√70²-4(1)(-1160)/2
x = -70±√4900+4640)/2
x = -70±(√4900+4640)/2
x = -70±√9540/2
x = -70±97.7/2
x = -70+97.7/2
x = 27.7/2
x = 13.85mph
x ≈ 14 mph
Hence, the speed(s) at which the car gets 9 mpg to the nearest mph is 14mph
