Give a real-life situation for the sum -15 + 10.
2 answers:
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1. Line l; point P not on l.( Take a line I and mark point P outside it or on the line.So from point P there are infinite number of lines out of which only one line is parallel to line I. Suppose you are taking point P on line I, from that point P also infinite number of lines can be drawn but only one line will be coincident or parallel to line I.
2. Plane R is parallel to plane S; Plane T cuts planes R and S.(Imagine you are sitting inside a room ,consider two walls opposite to each other as two planes R and S and floor on which you are sitting as third plane T ,so R and S are parallel and plane T is cutting them so in this case their lines of intersect .But this is not possible in each and every case, suppose R and S planes are parallel to each other and Plane T cuts them like two faces of a building and third plane T is stairs or suppose it is in slanting position i.e not parallel to R and S so in this case also lines of intersection will be parallel.
3. △ABC with midpoints M and N.( As you know if we take a triangle ABC ,the mid points of sides AB and AC being M and N, so the line joining the mid point of two sides of a triangle is parallel to third side and is half of it.
4.Point B is between points A and C.( Take a line segment AC. Mark any point B anywhere on the line segment AC. Three possibilities arises
(i) AB > BC (ii) AB < BC (iii) AB = BC
Since A, B,C are collinear .So in each case
Noticing that there is a pattern of repetition in the question (the numbers are repeated twice), we are assuming that the mean number of words per minute is 88, the standard deviation is of 14 WPM, as well as the number of sixth graders is 137, and that there is a need to estimate the probability that the sample mean would be greater than 89.87.
Answer:
"The probability that the sample mean would be greater than 89.87 WPM" is about .
Step-by-step explanation:
This is a problem of the <em>distribution of sample means</em>. Roughly speaking, we have the probability distribution of samples obtained from the same population. Each sample mean is an estimation of the population mean, and we know that this distribution behaves <em>normally</em> for samples sizes equal or greater than 30 . Mathematically
[1]
In words, the latter distribution has a mean that equals the population mean, and a standard deviation that also equals the population standard deviation divided by the square root of the sample size.
Moreover, we know that the variable Z follows a <em>normal standard distribution</em>, i.e., a normal distribution that has a population mean and a population standard deviation
.
[2]
From the question, we know that
- The population mean is
WPM
- The population standard deviation is
WPM
We also know the size of the sample for this case: sixth graders.
We need to estimate the probability that a sample mean being greater than WPM in the <em>distribution of sample means</em>. We can use the formula [2] to find this question.
The probability that the sample mean would be greater than 89.87 WPM
This is a <em>standardized value </em> and it tells us that the sample with mean 89.87 is 1.56<em> standard deviations</em> <em>above</em> the mean of the sampling distribution.
We can consult the probability of P(z<1.56) in any <em>cumulative</em> <em>standard normal table</em> available in Statistics books or on the Internet. Of course, this probability is the same that . Then
However, we are looking for P(z>1.56), which is the <em>complement probability</em> of the previous probability. Therefore
Thus, "The probability that the sample mean would be greater than 89.87 WPM" is about .