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2 years ago

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if A and B together can do a piece of work in 10 days and B along can do it in 15 days, how many part of the work does A complet

e in 6 days

1 answer:

anzhelika [568]2 years ago

8 0

Answer:

1/5

Step-by-step explanation:

Well work can be defined as: $work = rate \ *\ time$

where rate=amount of work that can be done in one unit of time

let a = rate of work A does in a day

let b = rate of work B does in a day

this means that: $10a + 10b=1$ where work=1 and it just means the entire job has been completed.

Since b can do it alone in 15 days, this means that: $15b=1$

If we divide by 15 here, we get the equation: $b=\frac{1}{15}$

We can now use this definition to substitute it into the first equation we made.

$10a + 10(\frac{1}{15}) = 1$

Multiply the 10 and 1/15

$10a+\frac{2}{3}=1$

subtract 2/3 from both sides

$10a=\frac{1}{3}$

Now divide both sides by 10

$a=\frac{1}{30}$

Now multiply this by 6, since we a represents the amount of work that can be done in a day, we want to find how many parts of the work can be done by a in 6 days

$6a=\frac{6}{30}$

Now divide both the numerator and denominator by 6

$a=\frac{1}{5}$

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3 years ago

A player of a video game is confronted with a series of opponents and has an 80% probability of defeating each one. Success with

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Answer:

(a) The PMF of <em>X</em> is: $P(X=k)=(1-0.20)^{k-1}0.20;\ k=0, 1, 2, 3....$

(b) The probability that a player defeats at least two opponents in a game is 0.64.

(c) The expected number of opponents contested in a game is 5.

(d) The probability that a player contests four or more opponents in a game is 0.512.

(e) The expected number of game plays until a player contests four or more opponents is 2.

Step-by-step explanation:

Let <em>X</em> = number of games played.

It is provided that the player continues to contest opponents until defeated.

(a)

The random variable <em>X</em> follows a Geometric distribution.

The probability mass function of <em>X</em> is:

$P(X=k)=(1-p)^{k-1}p;\ p>0, k=0, 1, 2, 3....$

It is provided that the player has a probability of 0.80 to defeat each opponent. This implies that there is 0.20 probability that the player will be defeated by each opponent.

Then the PMF of <em>X</em> is:

$P(X=k)=(1-0.20)^{k-1}0.20;\ k=0, 1, 2, 3....$

(b)

Compute the probability that a player defeats at least two opponents in a game as follows:

P (X ≥ 2) = 1 - P (X ≤ 2)

= 1 - P (X = 1) - P (X = 2)

$=1-(1-0.20)^{1-1}0.20-(1-0.20)^{2-1}0.20\\=1-0.20-0.16\\=0.64$

Thus, the probability that a player defeats at least two opponents in a game is 0.64.

(c)

The expected value of a Geometric distribution is given by,

$E(X)=\frac{1}{p}$

Compute the expected number of opponents contested in a game as follows:

$E(X)=\frac{1}{p}=\frac{1}{0.20}=5$

Thus, the expected number of opponents contested in a game is 5.

(d)

Compute the probability that a player contests four or more opponents in a game as follows:

P (X ≥ 4) = 1 - P (X ≤ 3)

= 1 - P (X = 1) - P (X = 2) - P (X = 3)

$=1-(1-0.20)^{1-1}0.20-(1-0.20)^{2-1}0.20-(1-0.20)^{3-1}0.20\\=1-0.20-0.16-0.128\\=0.512$

Thus, the probability that a player contests four or more opponents in a game is 0.512.

(e)

Compute the expected number of game plays until a player contests four or more opponents as follows:

$E(X\geq 4)=\frac{1}{P(X\geq 4)}=\frac{1}{0.512}=1.953125\approx 2$

Thus, the expected number of game plays until a player contests four or more opponents is 2.

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3 years ago

What is the solution to the equation 7^3x ≈ 9 ?

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4 years ago

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Answer:

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Step-by-step explanation:

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The quadratic expression can be factored into binomials and set equal to 0 by the zero product property to find x.

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x-3 = 0 so x=3

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Now check each solution into the original equation to be sure it solve the solution and is not extraneous.

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Using translation concepts, it is found that the correct option regarding the function is:

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<h3>What is a translation?</h3>

A translation is represented by a change in the function graph, according to operations such as multiplication or sum/subtraction in it's definition.

The parent function is given by:

$f(x) = \sqrt{x}$

Which increases on (0, ∞).

The translated function is given by:

$g(x) = -2\sqrt{x - 3}$

With the translation, the domain is now (-3, ∞), and the function is decreasing, hence the correct option is given by:

The function h(x) is decreasing on the interval (3, ∞).

More can be learned about translation concepts at brainly.com/question/4521517

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2 years ago