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3 years ago

9( -7b - 6) and Check for Understanding- Distributive Property

Mathematics

1 answer:

alexdok [17]3 years ago

6 0

9(-7b-6)

-63b-54

What I did was multiply 9 by -7b to gt -63b. Then, I multiplied 9 by -6 to get -54. :) hope this helps

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2. Point A is located at (-8, -3) on the coordinate grid. If it is

musickatia [10]

Answer:

(-6, 6).

Step-by-step explanation:

The x-coordinate increases by 2 units and the y-coordinate by 9 units:

That is ( - 8 + 2, -3 + 9)

= (-6, 6).

7 0

3 years ago

Kelko will rent a car for the weekend. She can choose one of two plans. The first plan has an initial fee of $57 and cost an add

Delicious77 [7]

Questions (contd)

(a) For what amount of driving do the two plans cost the same?

(b) What is the cost when the two plans cost the same?

Answer:

(a) 100 miles

(b) $65

Step-by-step explanation:

Given

Plan 1:

$Initial\ Fee = \$57$

$Additional = \$0.08$ per mile

Plan 2:

$Initial\ Fee = \$50$

$Additional = \$0.10$ per mile

Solving (a): Number of miles when both plans are equal

Represent the distance with x and the cost with y

So:

Plan 1:

$y = 57 + 0.08 * x$

Plan 2:

$y = 50 + 0.10 * x$

To solve (a), we equate both plans together; i.e.

$y = y$

$57 + 0.08x = 50 + 0.10x$

Collect Like Terms

$0.08x - 0.10x= 50 - 57$

$-0.02x= -2$

Solve for x

$x = -2/-0.02$

$x = 100$

Hence, 100 mile would cost both plans the same

Solving (b): Cost when both plans are the same:

In this case, we simply substitute 100 for x in any of the y equation.

$y = 57 + 0.08 * x$

$y = 57 + 0.08 * 100$

$y = 57 + 8$

$y = 65$

<em>Hence, the amount is $65</em>

7 0

3 years ago

What is the solution to-5x=-75

Furkat [3]

Answer:

-15

Step-by-step explanation:

4 0

3 years ago

Read 2 more answers

Let $$X_1, X_2, ...X_n$$ be uniformly distributed on the interval 0 to a. Recall that the maximum likelihood estimator of a is $

Solnce55 [7]

Answer:

a) $\hat a = max(X_i)$

For this case the value for $\hat a$ is always smaller than the value of a, assuming $X_i \sim Unif[0,a]$ So then for this case it cannot be unbiased because an unbiased estimator satisfy this property:

$E(a) - a= 0$ and that's not our case.

b) $E(\hat a) - a= \frac{na}{n+1} - a = \frac{na -an -a}{n+1}= \frac{-a}{n+1}$

Since is a negative value we can conclude that underestimate the real value a.

$\lim_{ n \to\infty} -\frac{1}{n+1}= 0$

c) $P(Y \leq y) = P(max(X_i) \leq y) = P(X_1 \leq y, X_2 \leq y, ..., X_n\leq y)$

And assuming independence we have this:

$P(Y \leq y) = P(X_1 \leq y) P(X_2 \leq y) .... P(X_n \leq y) = [P(X_1 \leq y)]^n = (\frac{y}{a})^n$

$f_Y (Y) = n (\frac{y}{a})^{n-1} * \frac{1}{a}= \frac{n}{a^n} y^{n-1} , y \in [0,a]$

e) On this case we see that the estimator $\hat a_1$ is better than $\hat a_2$ and the reason why is because:

$V(\hat a_1) > V(\hat a_2)$

$\frac{a^2}{3n}> \frac{a^2}{n(n+2)}$

$n(n+2) = n^2 + 2n > n +2n = 3n$ and that's satisfied for n>1.

Step-by-step explanation:

Part a

For this case we are assuming $X_1, X_2 , ..., X_n \sim U(0,a)$

And we are are ssuming the following estimator:

$\hat a = max(X_i)$

$E(a) - a= 0$ and that's not our case.

Part b

For this case we assume that the estimator is given by:

$E(\hat a) = \frac{na}{n+1}$

And using the definition of bias we have this:

$E(\hat a) - a= \frac{na}{n+1} - a = \frac{na -an -a}{n+1}= \frac{-a}{n+1}$

Since is a negative value we can conclude that underestimate the real value a.

And when we take the limit when n tend to infinity we got that the bias tend to 0.

$\lim_{ n \to\infty} -\frac{1}{n+1}= 0$

Part c

For this case we the followng random variable $Y = max (X_i)$ and we can find the cumulative distribution function like this:

$P(Y \leq y) = P(max(X_i) \leq y) = P(X_1 \leq y, X_2 \leq y, ..., X_n\leq y)$

And assuming independence we have this:

$P(Y \leq y) = P(X_1 \leq y) P(X_2 \leq y) .... P(X_n \leq y) = [P(X_1 \leq y)]^n = (\frac{y}{a})^n$

Since all the random variables have the same distribution.

Now we can find the density function derivating the distribution function like this:

$f_Y (Y) = n (\frac{y}{a})^{n-1} * \frac{1}{a}= \frac{n}{a^n} y^{n-1} , y \in [0,a]$

Now we can find the expected value for the random variable Y and we got this:

$E(Y) = \int_{0}^a \frac{n}{a^n} y^n dy = \frac{n}{a^n} \frac{a^{n+1}}{n+1}= \frac{an}{n+1}$

And the bias is given by:

$E(Y)-a=\frac{an}{n+1} -a=\frac{an-an-a}{n+1}= -\frac{a}{n+1}$

And again since the bias is not 0 we have a biased estimator.

Part e

For this case we have two estimators with the following variances:

$V(\hat a_1) = \frac{a^2}{3n}$

$V(\hat a_2) = \frac{a^2}{n(n+2)}$

On this case we see that the estimator $\hat a_1$ is better than $\hat a_2$ and the reason why is because:

$V(\hat a_1) > V(\hat a_2)$

$\frac{a^2}{3n}> \frac{a^2}{n(n+2)}$

$n(n+2) = n^2 + 2n > n +2n = 3n$ and that's satisfied for n>1.

8 0

4 years ago

WILL GIVE BRAINLEST!!! solve the triangle and answers to the nearest tenth.

sineoko [7]

Answer:

Angle A is 29 degress Angle B is 61 Angle C is 90

Side AB is 5.8 Side BC is 2.8 and Side AC is 5.1

Step-by-step explanation:

Angle A is found using triangle interior theorem.

I found side AC by using law of sines

b/sin b= c/sin c

x/sin 61= 5.8/sin 90( which equal 1)

x=5.1

I found side BC by using pythagoren theorem.

a^2 + b^2=c^2

5.1^2+ b^2=5.8^2

26.01+b^2=36.64

b^2=7.63

b=approx 2.8.

8 0

3 years ago