What is the ratio 9 to 81

Which of the following will make a confidence interval narrower and more precise?

swat32

Answer:

B. Larger sample size and lower confidence level

Step-by-step explanation:

The margin of error of a confidence interval is given by the following formula:

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

z is related to the confidence level. The higher the confidence level, the higher the value of Z.

So, the margin of error is direct proportion to the confidence level and inverse proportional to the sample size.

We want to decrease the margin of error.

So the correct answer is:

B. Larger sample size and lower confidence level

6 0

3 years ago

A = a is an example of which algebraic property?

Lena [83]

A=A or a=a is an example of the reflexive property, it's like looking in a mirror of oneself, hence the name of the property.

8 0

3 years ago

Read 2 more answers

The scatter plot shows the number of text messages sent (x) and text messages received (y) by 10 students in a half hour.

juin [17]

Answer: It’s B

Step-by-step explanation:

6 0

2 years ago

Read 2 more answers

Find (r-s) (t-s) + (s-r) (s-t) for all numbers r, s, and t. (a) 0 (b) 2 (c) 2rt (d) 2(s-r) (t-s) (e) 2(r-s) (t-s)

lyudmila [28]

Notice that the 2 expressions have 2 common terms.

(r-s) is just (s-r) times (-1)

similarly

(t-s) is just (s-t) times (-1)

this means that :

(r-s) (t-s) + (s-r) (s-t)=-(s-r)[-(s-t)]+(s-r) (s-t)

the 2 minuses in the first multiplication cancel each other so we have:

-(s-r)[-(s-t)]+(s-r) (s-t)=(s-r) (s-t)+(s-r) (s-t)=2(s-r) (s-t)

Answer:

d)<span>2(s-r) (t-s) </span>

3 0

3 years ago

Read 2 more answers

Find the quadratic function y=f(x) whose graph has a vertex (−3,4) and passes through the point (−7,0). Write the function

olganol [36]

Answer:

Step-by-step explanation:

This is a parabola since a quadratic is a parabola. The standard form for a parabola is y = ax² + bx + c

but before we do that, we will use the vertex form, since it will make our work easier at the beginning.

First and foremost, when we plot the vertex and the given point, the vertex is higher up than is the point; that means that this parabola opens upside down, and its vertex form will be

y=-|a|(x - h)² + k

The absolute value is out in front of the a, so we know that the value of a is positive, but the quadratic itself is negative (upside down) and we will find that math takes care of that negative that needs to be out front. So we need to solve for a by filling in the x, y, h, and k values from the point and the vertex: x = -7, y = 0, h = -3, k = 4

0 = a(-7 - (-3))² + 4 and

0 = a(-7 + 3)² + 4 and

0 = a(-4)² + 4 and

0 = a(16) + 4 and

0 = 16a + 4 and

-4 = 16a so

$a=-\frac{1}{4}$