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13 days ago

Hubert wants to buy a car tire that has a full price of$245 plus an 8% sales tax. Which is the better offer, a 15%-off sale or a

$25 coupon?

Mathematics

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Using the extended Euclidean algorithm, find the multiplicative inverse of a. 1234 mod 4321 b. 24140 mod 40902

AnnZ [12381]

(a) The multiplicative inverse of 1234 (mod 4321) is x so that 1234*x ≡ 1 (mod 4321). We can apply Euclid's algorithm:

4321 = 1234 * 3 + 619

1234 = 619 * 1 + 615

619 = 615 * 1 + 4

615 = 4 * 153 + 3

4 = 3 * 1 + 1

Now we will express 1 as a linear combination of 4321 and 1234:

1 = 4 - 3

1 = 4 - (615 - 4 * 153) = 4 * 154 - 615

1 = 619 * 154 - 155 * (1234 - 619) = 619 * 309 - 155 * 1234

1 = (4321 - 1234 * 3) * 309 - 155 * 1234 = 4321 * 309 - 1082 * 1234

This reduces to

1 ≡ -1082 * 1234 (mod 4321)

Thus, the inverse is

-1082 ≡ 3239 (mod 4321)

(b) Since both 24140 and 40902 are even, their GCD cannot equal 1, indicating no inverse exists.

8 0

3 months ago

According to Consumer Digest (July/August 1996), the probable location of personal computers (PC) in the home is as follows: Adu

PIT_PIT [12445]

Answer:

a) 0.32

b) 0.68

c) Office or den

Step-by-step explanation:

a) The likelihood that a personal computer is located in a bedroom can be calculated by adding the probabilities of it being in an adult bedroom, child bedroom, or another bedroom:

$P(B) =P(adult)+P(child)+P(other)\\P(B) = 0.03+0.15+0.14\\P(B) =0.32$

b) The probability of a PC not being located in a bedroom is found by calculating 100% minus the probability of it being in a bedroom:

$P(Not\ B) = 1- P(B)\\P(Not\ B) =1-0.32\\P(Not\ B) =0.68$

c) The expected location for finding a personal computer in a randomly selected household is derived from the room most likely to contain a PC according to Consumer Digest. The Office or den ranks as the most likely place with a probability of 0.40.

A PC would most likely be found in the Office or den.

6 0

3 months ago

A bag contains chips of which 27.5 percent are blue. A random sample of 5 chips will be selected one at a time and with replacem

lawyer [12517]

Answer:

$\mu _{\hat{p}}= 0.275\\\\ \sigma_{\hat{p}}=0.1997$

Step-by-step explanation:

It is known that the mean and standard deviation of the sampling distribution of the sample proportion( $\hat{p}$ ) are represented as follows:-

$\mu _{\hat{p}}=p\\\\ \sigma_{\hat{p}}=\sqrt{\dfrac{p(1-p)}{n}}$

, where p= Population proportion and n = sample size.

Let p denote the proportion of blue chips.

According to the information provided, we have

p= 0.275

n= 5

Thus, the mean and standard deviation of the sampling distribution of the sample proportion of blue chips for samples of size 5 will be:

$\mu _{\hat{p}}= 0.275\\\\ \sigma_{\hat{p}}=\sqrt{\dfrac{ 0.275(1- 0.275)}{5}}\\\\=0.19968725547\approx0.1997$

Therefore, you will have the mean and standard deviation for the sample proportion of blue chips for samples of size 5:

$\mu _{\hat{p}}= 0.275\\\\ \sigma_{\hat{p}}=0.1997$

6 0

2 months ago

A flat circular plate has the shape of the region x2 + y2≤1. The plate, including the boundary where x2 + y2 = 1, is heated such

Leona [12618]

Setting both partial derivatives to zero results in a single critical point at $(x,y)=\left(\dfrac12,0\right)$ , located within the unit disk.

At this given point, the derivative value of the Hessian matrix is

$|H|=\begin{vmatrix}T_{xx}&T_{xy}\\T_{yx}&T_{yy}\end{vmatrix}=\begin{vmatrix}2&0\\0&4\end{vmatrix}=8>0$

and the second-order partial derivative with respect to $x$ yields

$T_{xx}\bigg|_{(x,y)=(1/2,0)}=2>0$

This suggests that the critical point represents a local minimum, marking it as the coldest area on the plate with a temperature of $T\left(\dfrac12,0\right)=-\dfrac14$ .

To find the hottest area on the plate, it must be located along the boundary. Let $x=\cos\theta$ and $y=\sin\theta$ , so that

$T(x,y)=T(\theta)=\cos^2\theta+2\sin^2\theta-\cos\theta$
$T(\theta)=\dfrac32-\cos\theta-\dfrac12\cos2\theta$

Thus, the plate's boundary (the circle $x^2+y^2=1$ ) is treated as a single variable function $\theta$ examined over $\theta\in[0,2\pi)$ . A single differentiation gives

$T'(\theta)=\sin\theta+\sin2\theta=0$
$\implies\theta=0,\theta=\dfrac{2\pi}3,\theta=\pi,\theta=\dfrac{4\pi}3$

You will discover that $T(\theta)$ achieves three extrema on the interval $(0,2\pi)$ , with relative maxima occurring at $\theta=\dfrac{2\pi}3$ and $\theta=\dfrac{4\pi}3$ , and a relative minimum at $\theta=\pi$ (and $\theta=0$ , if you wish to include that).

Our minimum has already been identified inside the plate - which you can check to have a lower temperature than at the points noted by $T(\theta)$ - and we identify two maxima at $\theta=\dfrac{2\pi}3$ and $\theta=\dfrac{4\pi}3$ , both showing a maximum temperature of $T=\dfrac94$ .

Reverting to Cartesian coordinates, these points match up with $\left(-\dfrac12,\pm\dfrac{\sqrt3}2\right)$ .

4 0

2 months ago