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2 years ago

A box of wood pieces contains wood cut into triangular, square, and

Mathematics

1 answer:

pogonyaev2 years ago

6 0

Answer:

There are 30 square pieces, 40 triangular pieces and 10 pentagonal pieces.

Step-by-step explanation:

Let x be the number of square pieces. If there are 10 more triangular pieces than square pieces, then there are (x + 10) triangular pieces. Let y be the number of pentagonal pieces.

1. There are 80 pieces of wood in the box, then

(x + 10) + x + y = 80

2. There are

3 sides in a triangular piece $\rightarrow$ there are 3(x + 10) sides in x + 10 pieces;
4 sides in a square piece $\rightarrow$ there are 4x sides in x pieces;
5 sides in a pentagonal piece $\rightarrow$ there are 5y sides in y pieces;
in total, there are 290 sides.

So,

3(x+10)+4x+5y=290

You get the system of two equations:

$\left\{\begin{array}{l}(x+10)+x+y=80\\3(x+10)+4x+5y=290\end{array}\right.\Rightarrow \left\{\begin{array}{l}2x+y=70\\7x+5y=260\end{array}\right.$

From the first equation,

$y=70-2x$

Substitute it into the second equation

$7x+5(70-2x)=260\\ \\7x+350-10x=260\\ \\-3x=260-350\\ \\-3x=-90\\ \\x=30\\ \\x+10=40\\ \\y=70-2\cdot 30=10$

Hence, there are 30 square pieces, 40 triangular pieces and 10 pentagonal pieces.

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7 is (14x)°

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John's commute to work is 20kmhr while Sheri's commute is 500mmin. Who has the fastest commute to work in mihrif 1.61km=1mi? A S

Andreyy89

Answer:

A) Sheri has the faster commute by 6.2 miles/hr.

Step-by-step explanation:

Given

John's commute to work $=20\ km/hr$

Sheri's commute to work $=500\ m/min$

$1.61\ km = 1\ mile$

John's commute to work in miles per hour = $\frac{20\ km}{1 hr}\times \frac{1\ mile}{1.61\ km}= 12.42\ miles/hr$

Sheri's commute to work in miles per hour = $\frac{500\ m}{1\ min}\times \frac{1\ km}{1000\ m}\times \frac{1\ mile}{1.61\ km}\times \frac{60\ min}{1\ hr}= 18.63\ miles/ hr$

We can see that Sheri has a faster commute.

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2 years ago

A supermarket has two customers waiting to pay for their purchases at counter I and one customer waiting to pay at counter II. L

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Answer:

b. 0.864

Step-by-step explanation:

Let's start defining the random variables.

Y1 : ''Number of customers who spend more than $50 on groceries at counter 1''

Y2 : ''Number of customers who spend more than $50 on groceries at counter 2''

If X is a binomial random variable, the probability function for X is :

$P(X=x)=(nCx)p^{x}(1-p)^{n-x}$

Where P(X=x) is the probability of the random variable X to assume the value x

nCx is the combinatorial number define as :

$nCx=\frac{n!}{x!(n-x)!}$

n is the number of independent Bernoulli experiments taking place

And p is the success probability.

In counter I :

Y1 ~ Bi (n,p)

Y1 ~ Bi(2,0.2)

$P(Y1=y1)=(2Cy1)(0.2)^{y1}(0.8)^{2-y1}$

With y1 ∈ {0,1,2}

And P( Y1 = y1 ) = 0 with y1 ∉ {0,1,2}

In counter II :

Y2 ~ Bi (n,p)

Y2 ~ Bi (1,0.3)

$P(Y2=y2)=(1Cy2)(0.3)^{y2}(0.7)^{1-y2}$

With y2 ∈ {0,1}

And P( Y2 = y2 ) = 0 with y2 ∉ {0,1}

(1Cy2) with y2 = 0 and y2 = 1 is equal to 1 so the probability function for Y2 is :

$P(Y2=y2)=(0.3)^{y2}(0.7)^{1-y2}$

Y1 and Y2 are independent so the joint probability distribution is the product of the Y1 probability function and the Y2 probability function.

$P(Y1=y1,Y2=y2)=P(Y1=y1).P(Y2=y2)$

$P(Y1=y1,Y2=y2)=(2Cy1)(0.2)^{y1}(0.8)^{2-y1}(0.3)^{y2}(0.7)^{1-y2}$

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P( Y1 = y1 , Y2 = y2) = 0 when y1 ∉ {0,1,2} or y2 ∉ {0,1}

b. Not more than one of three customers will spend more than $50 can mathematically be expressed as :

$Y1 + Y2 \leq 1$

$Y1 + Y2\leq 1$ when Y1 = 0 and Y2 = 0 , when Y1 = 1 and Y2 = 0 and finally when Y1 = 0 and Y2 = 1

To calculate $P(Y1+Y2\leq 1)$ we must sume all the probabilities that satisfy the equation :

$P(Y1+Y2\leq 1)=P(Y1=0,Y2=0)+P(Y1=1,Y2=0)+P(Y1=0,Y2=1)$

$P(Y1=0,Y2=0)=(2C0)(0.2)^{0}(0.8)^{2-0}(0.3)^{0}(0.7)^{1-0}=(0.8)^{2}(0.7)=0.448$

$P(Y1=1,Y2=0)=(2C1)(0.2)^{1}(0.8)^{2-1}(0.3)^{0}(0.7)^{1-0}=2(0.2)(0.8)(0.7)=0.224$

$P(Y1=0,Y2=1)=(2C0)(0.2)^{0}(0.8)^{2-0}(0.3)^{1}(0.7)^{1-1}=(0.8)^{2}(0.3)=0.192$

$P(Y1+Y2\leq 1)=0.448+0.224+0.192=0.864\\P(Y1+Y2\leq 1)=0.864$

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2 years ago

A marketing representative wants to estimate the proportion of people in a state who like the new design on the packaging of a c

Effectus [21]

Answer:

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Step-by-step explanation:

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