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2 answers:
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Answer:
Step-by-step explanation:
We have to perform one sample proportion test. To do so we have to proceed through following steps.
(1) We have to collect data about vehicle sales in last 20 years.
(2) Using random number table or random number generator or otherwise we have to select sample of vehicles from the list of sale. In this step, we have to keep an eye on the fact that sample is to be selected from all years (all of 20). Using stratified random sampling by dividing vehicles sold over different years is an effective way to do so. That means, we may divide vehicles sold into 20 homogeneous strata over 20 years and select sample from each strata.
(3) After selecting sample of vehicles we have to communicate to corresponding vehicle owners to gather information about that particular vehicle.
(4) We have to note number of vehicles which are still on the road.
Suppose, we have selected n vehicles as sample and after communicating we found that \tiny r of those are still on the road.
We have to test for null hypothesis
against the alternative hypothesis
Our test statistic is given
here,
We then calculate corresponding p-value.
We reject our null hypothesis if , level of significance.
According to our obtained p-value and level of significance we proceed to certain conclusion.
Answer:
(x²-10x+33)/(-8) = y
Step-by-step explanation:
The distance between any point on a parabola from both its focus and directrix are the same.
Let's say we have a point (x,y) on the parabola. We can then say that using the distance formula,
is the distance between (x,y) and the focus. Similarly, the distance between (x,y) and the directrix is |y-1| (I use absolute value here because distance is always positive). We can find this equation by taking the shortest distance from the point to the line. Because the closest point to the line will be the same x value as the point itself, the distance is simply the distance between the y value of the point and the y value of the directrix.
Equating the two equations given, we have
square both sides to get
(x-5)²+(y+3)²=(y-1)²
expand the y components
(x-5)² + y²+6y+9 = y²-2y+1
subtract y²+6y+9 from both sides
(x-5)² = -8y - 8
expand the x components
x²-10x+25 = -8y - 8
add 8 to both sides to isolate the -8y
x²-10x+33 = -8y
divide both sides by -8 to isolate y
(x²-10x+33)/(-8) = y