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Dmitriy789 [7]
3 years ago
13

50 POINTSNeed help with these 3 questions. ​

Mathematics
2 answers:
emmasim [6.3K]3 years ago
6 0

Answer:

1 answer in first photo

2 answer in second photo

3 answer - in third photo

hope it will help you

mr_godi [17]3 years ago
4 0

Answer:

1st: 1/x (6mins). 2nd: 12. 1 day.

Step-by-step explanation:

1st:

One person can do a certain job in ten minutes, and another person can do the same job in fifteen minutes. How many minutes will they take to do the job together?

One person's rate:: 1/10 job/hr

Other person's rate:: 1/15 job/hr

Together rate:: 1/x job/hr

If x represents how many minutes to do the job together, then how much of the job does the slowest person do? 6 minutes.

-------------------

2nd:

Given : The sum of one-third of a number and three-fourths of the number exceeds that number by one.

To find : Which equation could be used to find the number

Let a number  = n

One third of a number = .

Three - fourths of the number  =  .

Sum of their is  exceeds that number by one.

+  = n +1.

Taking common denominator

= n+1 .

= n+1.

On subtracting n both sides.

-n = 1

Taking common denominator

= 1

= 1

On multiplying by 12 both sides

n= 12.

-------------------

3rd:

Person A can finish job in 6 days

Person B can finish job in 2 days

Person C can finish job in 3 days.

So let us present it this way.

x/6 + x/2 + x/3 = number of days

Find common denominator which is 6.

x/6 +3x/6 + 2x/6 = days

6x/6 = days

x = 1 day.

-------------------

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ollegr [7]
Simplifying
3x + 4 = 7 + -2x

Reorder the terms:
4 + 3x = 7 + -2x

Solving
4 + 3x = 7 + -2x

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '2x' to each side of the equation.
4 + 3x + 2x = 7 + -2x + 2x

Combine like terms: 3x + 2x = 5x
4 + 5x = 7 + -2x + 2x

Combine like terms: -2x + 2x = 0
4 + 5x = 7 + 0
4 + 5x = 7

Add '-4' to each side of the equation.
4 + -4 + 5x = 7 + -4

Combine like terms: 4 + -4 = 0
0 + 5x = 7 + -4
5x = 7 + -4

Combine like terms: 7 + -4 = 3
5x = 3

Divide each side by '5'.
x = 0.6

Answer: x = 0.6
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3 years ago
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Find the standard deviation of the following data. Round your answer to one decimal place. x 0 1 2 3 4 5 P(X
lbvjy [14]

Answer:

<em></em>\sigma = 1.8<em></em>

<em></em>

Step-by-step explanation:

Given

\begin{array}{ccccccc}x & {0} & {1} & {2} & {3} & {4}& {5} \ \\ P(x) & {0.2} & {0.1} & {0.1} & {0.2} & {0.2}& {0.2} \ \end{array}

Required

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First, calculate the expected value E(x)

E(x) = \sum x * P(x)

So, we have:

E(x) = 0 * 0.2 + 1 * 0.1 + 2 * 0.1 + 3 * 0.2 + 4 * 0.2 + 5  * 0.2

E(x) = 2.7

Next, calculate E(x^2)

E(x^2) = \sum x^2 * P(x)

So, we have:

E(x^2) = 0^2 * 0.2 + 1^2 * 0.1 + 2^2 * 0.1 + 3^2 * 0.2 + 4^2 * 0.2 + 5^2  * 0.2

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The standard deviation is:

\sigma = \sqrt{E(x^2) - (E(x))^2}

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alex41 [277]

Complete the square to rewrite the quadratic:

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Any real number squared becomes non-negative, so the quadratic expression has a minimum value of 31/8, which is greater than 0, and so there are no (real) <em>x</em> for which <em>y</em> = 0.

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