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2 years ago

12

Recall the chapter example which described the fact that the mean IQ in large, diverse and the standard deviation is 15. Your sa

mple of 300 members populations is 100 your community gave you a mean 99% confidence level for this sample. Which of the following your answer? the margin of error for the figures comes closest to 1Q score of 1os. Calculate t A. 10.95 B. ±1.96 C. 12.23 D. 11.16 E. None of the above

1 answer:

natulia [17]2 years ago

7 0

Given Information:

Population size = n = 300

standard deviation = σ = 15

confidence level = 99%

Required Information:

Margin of error = ?

Step-by-step explanation:

The margin of error is a measure of the effectiveness of your survey.

Margin of error = z*(σ/√n)

z-score corresponding to 99% confidence level = 2.58

Margin of error = ±2.58*(15/√300)

Margin of error = ±2.58*(0.866)

Margin of error = ±2.23

Hence the correct option is C ±2.23

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In jims class, 5 times has many students take the bus as those who walk. A total of 24 students walk or take the bus. How many m

lubasha [3.4K]

Take bus=5 times walk
b=5w
b+w=24
sub 5w for b
5w+w=24
6w=24
divide both sides by 6
w=4

sub back
b=5w
b=5(4)
b=20

bus-walk=20-4=16

answer is 16 more take the bus than walk

7 0

2 years ago

Daniel [21]

Answer:

Step-by-step explanation:

As the statement is ‘‘if and only if’’ we need to prove two implications

$f : X \rightarrow Y$ is surjective implies there exists a function $h : Y \rightarrow X$ such that $f\circ h = 1_Y$ .
If there exists a function $h : Y \rightarrow X$ such that $f\circ h = 1_Y$ , then $f : X \rightarrow Y$ is surjective

Let us start by the first implication.

Our hypothesis is that the function $f : X \rightarrow Y$ is surjective. From this we know that for every $y\in Y$ there exist, at least, one $x\in X$ such that $y=f(x)$ .

Now, define the sets $X_y = \{x\in X: y=f(x)\}$ . Notice that the set $X_y$ is the pre-image of the element $y$ . Also, from the fact that $f$ is a function we deduce that $X_{y_1}\cap X_{y_2}=\emptyset$ , and because $f$ the sets $X_y$ are no empty.

From each set $X_y$ choose only one element $x_y$ , and notice that $f(x_y)=y$ .

So, we can define the function $h:Y\rightarrow X$ as $h(y)=x_y$ . It is no difficult to conclude that $f\circ h(y) = f(x_y)=y$ . With this we have that $f\circ h=1_Y$ , and the prove is complete.

Now, let us prove the second implication.

We have that there exists a function $h:Y\rightarrow X$ such that $f\circ h=1_Y$ .

Take an element $y\in Y$ , then $f\circ h(y)=y$ . Now, write $x=h(y)$ and notice that $x\in X$ . Also, with this we have that $f(x)=y$ .

So, for every element $y\in Y$ we have found that an element $x\in X$ (recall that $x=h(y)$ ) such that $y=f(x)$ , which is equivalent to the fact that $f$ is surjective. Therefore, the prove is complete.

3 0

2 years ago

A driver averages 42 miles per hour and took 15 hours to travel between two cities what is the distance between the two cities

pishuonlain [190]

Answer:

The distence bettween the two cities is 630miles

Step-by-step explanation:

So you take 42 and multiply it by 15 and you get 630.

5 0

2 years ago

How many different passwords are possible if each password consists of six characters where each character is either an uppercas

irga5000 [103]

<span><span>1,867,866,560</span><span>1,867,866,560</span></span><span>.</span>

4 0

2 years ago

Explain how you know which method you should use to solve a rational equation.

notsponge [240]

<u>Methods to solve rational equation:</u>

Rational equation:

A rational equation is an equation containing at least one rational expression.

Method 1:

The method for solving rational equations is to rewrite the rational expressions in terms of a common denominator. Then, since we know the numerators are equal, we can solve for the variable.

For example,

$\frac{1}{2}=\frac{x}{2}\Rightarrow x=1$

This can be used for rational equations with polynomials too.

For example,

$\frac{1+x}{x-3}=\frac{4}{x-3}\Rightarrow(1+x)=4 \Rightarrow x=3$

When the terms in a rational equation have unlike denominators, solving the equation will be as follows

$\frac{x+2}{8}=\frac{3}{4}$

$\Rightarrow\frac{x+2}{1}=\frac{3\times8}{4}\Rightarrow{x+2}=2\times3$

$\Rightarrow{x+2}=6\Rightarrow x=6-2\Rightarrow x=4$

Method 2:

Another way of solving the above equation is by finding least common denominator (LCD)

$\frac{x+2}{8}=\frac{3}{4}$

Factors of 4: $1\times2\times2$

Factors of 8: $1\times2\times2\times2$

The LCD of 4 and 8 is 8. So, we have to make the right hand side denominator as 8. This is done by the following step,

$\Rightarrow\frac{x+2}{8}=\frac{3}{4}\times{2}{2}$

we get,

$\Rightarrow\frac{x+2}{8}=\frac{6}{8}$

On cancelling 8 on both sides we get,

$\Rightarrow(x+2)=6\rightarrow x=6-2\rightarrow x=4$

Hence, these are the ways to solve a rational equation.

7 0

2 years ago