2g-h/f=5 solve for g

How many 4 digit numbers consisting of only the digits 2,4,6 and 8 are divisible by 4

Blababa [14]

Answer:

digits used once: 12
repeated digits: 128

Step-by-step explanation:

In order for a number to be divisible by 4, its last two digits must be divisible by 4. This will be the case if either of these conditions holds:

the ones digit is an even multiple of 2, and the tens digit is even
the ones digit is an odd multiple of 2, and the tens digit is odd.

We must count the ways these conditions can be met with the given digits.

__

Since we only have even numbers to work with, the ones digit must be an even multiple of 2: 4 or 8. (The tens digit cannot be odd.) The digits 4 and 8 comprise half of the available digits, so half of all possible numbers made from these digits will be divisible by 4.

<h3>digits used once</h3>

If the numbers must use each digit exactly once, there will be 4! = 24 of them. 24/2 = 12 of these 4-digit numbers will be divisible by 4.

<h3>repeated digits</h3>

Each of the four digits can have any of four values, so there will be 4^4 = 256 possible 4-digit numbers. Of these, 256/2 = 128 will be divisible by 4.

7 0

1 year ago

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Rex, Paulo, and Ben are standing on shore watching for dolphins. Paulo sees one surface directly in front of him about a hundred

Ksivusya [100]

1. $m\angle BAC=m\angle CAD,\ m\angle ACB=m\angle ADC=90^{\circ}$ , then $m\angle ABC=m\angle ACD$ and triangles ADC and ACB are similar by AAA theorem.

2. The ratio of the corresponding sides of similar triangles is constant, so

$\dfrac{AC}{AB}= \dfrac{AD}{AC}$ .

3. Knowing lengths you could state that $\dfrac{b}{c}= \dfrac{e}{b}$ .

4. This ratio is equivalent to $b^2=ce$ .

5. $m\angle ABC=m\angle CBD,\ m\angle ACB=m\angle CDB=90^{\circ}$ , then $m\angle BAC=m\angle BCD$ and triangles BDC and BCA are similar by AAA theorem.

6. The ratio of the corresponding sides of similar triangles is constant, so

$\dfrac{BC}{BD}= \dfrac{AB}{BC}$ .

7. Knowing lengths you could state that $\dfrac{a}{d}= \dfrac{c}{a}$ .

8. This ratio is equivalent to $a^2=cd$ .

9. Now add results of parts 4 and 8:

$b^2+a^2=ce+cd$ .

10. c is common factor, then:

$b^2+a^2=c(e+d)$ .

11. Since $e+d=c$ you have $a^2+b^2=c\cdot c=c^2$ .

7 0

3 years ago

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An instructor in a college class recently gave an exam that was worth a total of 100 points. The instructor inadvertently made t

solniwko [45]

Answer:

B) Method 2 will increase the standard deviation of the students' scores.

Step-by-step explanation:

Given that an instructor in a college class recently gave an exam that was worth a total of 100 points.

The average score for his students was 43 and the standard deviation of the scores was 5 points.

And now he is considering two different strategies for rescaling the exam results of which:

Method 1 = Add 17 points to everyone's score.

Method 2 = Multiply everyone's score by 1.7 .

And we have to check what will be the impact of these methods on the standard deviation of the students' scores.

For this let us consider a simple example to understand this:

Firstly, Formula for calculating Standard Deviation = $\sqrt{\frac{\sum (X-Xbar)^{2}}{n-1}}$

Suppose,

X X - Xbar $(X - Xbar)^{2}$

3 3 - 6 = -3 -3 * -3 = 9

5 5 - 6 = -1 -1 * -1 = 1

10 10 - 6 = 4 4 * 4 = 16

<em>Mean of above data, Xbar</em> = $\frac{3+ 5+10}{3}$ = 6

<em>Standard Deviation of data </em>= $\sqrt{\frac{26}{3-1} }$ = 3.6055

Now let us suppose that we multiply each value of above data with 2 so the new data will be:

X X - Xbar $(X - Xbar)^{2}$

3*2 = 6 6 - 12 = -6 -6 * -6 = 36

5*2 = 10 10 - 12 = -2 -2 * -2 = 4

10*2 =20 20 - 12 = 8 8 * 8 = 64

<em>Mean of new data, Xbar </em>= $\frac{6+ 10+20}{3}$ = 12

<em>Standard Deviation of new data</em> = $\sqrt{\frac{104}{3-1} }$ = 7.2111

<em>Hence, we see that when we multiply any value to the data the standard deviation will increase and in other words it will multiplied by that value which value we multiplied with each data value i.e. when we multiply each data value with 2 the standard deviation also get multiplied by as </em>

3.6055 * 2 = 7.2111

Therefore option B is correct that Method 2 will increase the standard deviation of the students' scores.

<em>And on the other hand Similarly by adding any constant to the data the Standard Deviation will remain same. Therefore Method 1 will have no impact on standard deviation of the students' scores.</em>

8 0

3 years ago

I’m confused. List the following numbers in order from least to greatest. —1.4, 0.75, —2 1/3, 21%, 4/5

Anna007 [38]

The answer is -21/3, -1.4, 21%, 4/5,0.75.

You have to convert them to the same unit.

6 0

3 years ago

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How do you solve the equation (X+3)^3=81

solmaris [256]

$(x+3)^3=81\\
x+3=\sqrt[3]{81}\\
x+3=3\sqrt[3]3\\
x=3\sqrt[3]3-3\\
$