In a study of reaction times to a specific stimulus, a psychologist recorded these data (in seconds). Find the variance and standard deviation. Use a TI-83 Plus/TI-84 Plus calculator and round the answers to at least two decimal places.

Answer:

[tex]x = -10 + 4 \sqrt7 \ , \ x = -10 - 4 \sqrt7[/tex]

Step-by-step explanation:

x²+20x-12=0

a = 1, b = 20, c = -12

[tex]x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2x}[/tex]

[tex]x = \frac{-20 \pm \sqrt{448}}{2}\\\\x = \frac{-20 \pm \sqrt{8 \times 8 \times 7}}{2}\\\\x = \frac{-20 + 8\sqrt{7}}{2} \ , \ x = \frac{-20 - 8 \sqrt7}{2}\\\\x = \frac{-10 + 4\sqrt{7}}{1} \ , \ x = \frac{-10 - 4 \sqrt7}{1}\\\\x = -10 + 4 \sqrt7 \ , \ x = -10 - 4 \sqrt7[/tex]

Answer:

so the total is 20 and its at ten so

10/20=5/10=1/2

so 50 percent

plzzz brainlest

Answer:

Minimum average cost = 743.75

Number of dvds to achieve the cost = 62.5

Step-by-step explanation:

Given the cost equation

C = 0.04x² − 5x + 900

To Obtian the minimum average cost ;

Find dc/dx = 0

Diffentiate cost, c it ith respect to x

dc/dx = 2(0.04x) - 5

dc/dx = 0.08x - 5 = 0

0.08x = 5

x = 5 / 0.08

x = 62.5

Substitute the value of x into C to obtain the minimum average cost

C = 0.04(62.5)² - 5(62.5) + 900

C = 743.75

Answer:

p-value of 0.1357 > 0.1, which means that we do not reject the null hypothesis, that is, there is not sufficient evidence to conclude that the population mean is above 85.

Step-by-step explanation:

Decision:

If the p-value is greater than the significance level, we accept the null hypothesis. Otherwise, we reject the null hypothesis.

In this question:

Null hypothesis:

μ = 85

Alternate hypothesis:

a: μ > 85

SPSS reports a two-tailed p-value of 0.2714.

We are testing if the mean is greater than a value, which is a one-tailed test, so the p-value is of 0.2714/2 = 0.1357

Decision:

p-value of 0.1357 > 0.1, which means that we do not reject the null hypothesis, that is, there is not sufficient evidence to conclude that the population mean is above 85.

Answer:

$16.40

Step-by-step explanation:

Answer:

98.40

Step-by-step explanation:

First find the tip

82* 20%

82* .20

16.40

Add the tip to the cost of the mean

82+16.40

98.40

Answer:

its 4/2 or simplified to 2/1

Step-by-step explanation:

mark me brainliest pls

Answer:

First term: 2x+1

Second term: 3x+3

Step-by-step explanation:

The coefficient of x is going up by 1 time each time while the constant term is going up by 2.

We are looking at these two questions basically:

1) What are the first two terms in?

_,_,4,5,6,7,8

2) What are the first two terms in?

_,_,5,7,9,11,13

Answers:

1) Since the sequence is going up by 1 reading left to right, then right to left it's going down by 1.

So before 4, we have 3.

Before 3, we have 2.

The sequence for the coefficient of x is 2,3,4,5,6,7,8

2) Since the sequence is going up by 2 from left to right, then it's going down by 2 reading right to left.

So before 5, we have 3.

Before 3, we have 1.

The sequence for the constant term is 1,3,5,7,9,11,13.

So first two terms of the sequence in ascending order according to the sequence is:

2x+1

3x+3

Answer:

What product

Step-by-step explanation:

Answer:

you need to zoom in i cant see plz :)

Step-by-step explanation:

Answer:

the second green shape because the first one is a rectangle which has 2 equal sides

Answer:

the third orange one

Step-by-step explanation:

i have the same question and these 2 show up as answers on both so it has to be this one

Step-by-step explanation:

20 ml is your answer

i hope it helps u

Answer:

If I'm reading it correctly the answer should be 20.

To get that answer all you do is 4x5.

Step-by-step explanation:

the final position = (-3+2 , -3+6) => (-1, 3)

the distance from the origin point =

√(2²+6²) = √(4+36) = √40 units or 6.3 units

the direction = tan~¹ 6/2 = 71.6°

Answer:

-415 meters

Step-by-step explanation:

As it was already -300 and it decended even more

so:

-300-`115=-415

Answer:

The answer is A, -415 meters.

Step-by-step explanation:

All right, so the key words we need here are -300, descends, and 115.

Descends means go lower, or in this case, subtract.

We are already at -300 and we descend 115, so we are going to subtract.

Subtracting a number is the same as adding the negative of that number.

-300 + -115 = -415

The answer is A, -415 meters.

Hope this helps, please mark brainliest if possible. :)

Answer:

The other point lies on the graph is (0, - 8).

Step-by-step explanation:

Point (3, - 4) lies on the graph [tex]y = (x -5)^2 + K[/tex]

So, put x = 3 and y = - 4 in the equation.

[tex]- 4 = ( 3 -5)^2 + K\\\\- 4 = 4 + K \\\\K= - 8[/tex]

So, the equation of graph is

[tex]y = (x - 5)^2 -8[/tex]

Let x = 5 lies on the graph so

[tex]y = (5 -5)^2 -8 \\\\y = -8[/tex]

So, the other point lies on the graph is (0, - 8).

Answer:

106

Step-by-step explanation:    ts 6 9 21  30

After Monday

    102 + Tuesday + Wednesday + Thursday + Friday         After

    102 +       1        +        1             +        1        +      1       =       106

Answer:

11 pounds

Step-by-step explanation:

You would do 88 divided by 8 to get 11

9514 1404 393

Answer:

  1. 5 seconds

  2. 4.5 seconds

Step-by-step explanation:

Both of these questions can be solved the same way. Each quadratic gives height as a function of time. You're interested in the time at which the height is zero. Factor the quadratic and find the positive value of x that makes the relevant factor be zero.

__

1) y = -15x(x -5)

  x = 5 makes the second factor zero

The golf ball is in the air 5 seconds.

__

2) y = -12x(x -4.5)

  x = 4.5 makes the second factor zero

The football is in the air for 4.5 seconds.

_____

Additional comment

The "zero product rule" tells you a product will be zero if and only if one or more of the factors is zero. When a factored quadratic (or any other polynomial) is zero, one of the factors must be zero. If the factor is of the form (ax+b), then the corresponding solution is ...

  ax+b = 0   ⇒   ax = -b   ⇒   x = -b/a

That is, once you have the factored form, you can write the solutions "by inspection."

Answer:

C

Step-by-step explanation:

[tex]\frac{2}{3} (x + 2) - \frac{1}{3} (x - 2)[/tex]

First, multiply [tex]\frac{2}{3}[/tex] to [tex](x + 2)[/tex] , then [tex]\frac{1}{3}[/tex] to [tex](x - 2)[/tex], after you have done that, you would get an equation looking like this[tex]\\[/tex]:

[tex]\frac{2}{3} x + \frac{4}{3} - \frac{1}{3}x - \frac{2}{3}[/tex]

Next, add and/or subtract the fractions with the variables together and the ones without together, and that is how you get to your final answer

[tex]\frac{1}{3}x + \frac{2}{3}[/tex]

Answer:

[tex] \frac{16}{33} [/tex]

Step-by-step explanation:

[tex]x = 0.48... \\ 100 \times x = 0.48 \times 100 \\ 100x - x = 48.48.. - 0.48 \\ 99x = 48 \\ \frac{99x}{99} = \frac{48}{99} \\ x = \frac{16}{33} [/tex]

Answer:

The cosine of ∠V is of 0.74.

Step-by-step explanation:

Relations in a right triangle:

The cosine of an angle is given by the length of the adjacent side divided by the length of the hypotenuse.

XW = 65, WV = 97, and VX = 72.

[tex]\sqrt{65^2+72^2} = 97[/tex], and thus, this is a right triangle.

What is the value of the cosine of ∠V to the nearest hundredth?

The hypotenuse is the largest side, that is, WV = 97.

The adjacent side of angle V is VX = 72. So

[tex]\cos{B} = \frac{72}{97} = 0.74[/tex]

The cosine of ∠V is of 0.74.

Answer:

2*3

Step-by-step explanation:

multiplying 2 the difference subtraction of 9-7 your answer is  2*3

ok thats cool ig what do you need help with

Answer:

A

Step-by-step explanation:

Have a nice day :)

The butterfly and moth develop through a process called metamorphosis. This is a Greek word that means transformation or change in shape. There are four stages in the metamorphosis of butterflies and moths: egg, larva, pupa, and adult.

mark me brainliesttt :)))

Answer:

f(3) = -8

Step-by-step explanation:

f(3) means find the y value when x=3

Using the graph the y value when x =3 is -8

f(3) = -8

Answer:

$27.2

Step-by-step explanation:

680x0.04=. 27.2

She made $27.2 last week

Answer:

C = 5^2 * Pi * 8

Step-by-step explanation:

Formula = [tex]r^{2}[/tex]*Pi*h

r = d / 2

d=10, so r=5

h = 8

Answer:

First you need to state the equation that represents the function.

Investment is $200 and interest rate is 5%, y is the amount of money after x periods.

Note that after 1 period the amount of money is 200 plus 5% interest, which is 200 + 5%(200) = 200 (1 +5%) = 200 (1 + 0.05) = 200 (1.05)

After 2 periods the amount is 200(1.05)*(1.05) = 200 (1.05)^2

After 3 periods the amount is 200 (1.05)^3

And now you can deduce that after x periods y = 200 (1.05)^x

You can then analyze the function to predict the shape and critical points of the graph.

The answers are based in the initial value and the increasing factor.

The initial value is when x = 0, which yields to y = 200 (1.05)^0 = 200*1 = 200

And the increasing factor is 1.05 because any value is the previos one times 1.05.

Step-by-step explanation:

Answer:

D

Step-by-step explanation:

compare the numbers