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3 years ago

Solve this equation v-10=-9

2 answers:

8 0

V-10=-9
+10= +10
V= 1

You have to get rid of the number beside the variable that you are solving for in order to get your answer.

andrew11 [14]3 years ago

6 0

First add 10 on both sides. So it will be v = 1.

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Which is the vertex of x^2 + 10x = - 17?

Valentin [98]

Answer:

(-5, -8)

Step-by-step explanation:

3 0

2 years ago

The average lifetime of a set of tires is 3.4 years. The manufacturer will replace any set of tires failing within three years o

ICE Princess25 [194]

Answer: the probability that the tires will fail within three years of the date of purchase is 0.12

Step-by-step explanation:

The average lifetime of a set of tires is 3.4 years. It means that μ = 3.4

Decay parameter, m = 1/3.4 = 0.294

The probability density function is

f(x) = me^-mx

Where x is a continuous random variable representing the time interval of interest(the reliability period that we are testing)

Since x = 3 years,

Therefore, the probability that the tires will fail within three years of the date of purchase is

f(3) = 0.294e^-(0.294 × 3)

f(3) = 0.294e^- 0.882

f(3) = 0.12

7 0

3 years ago

5.2.14. For the negative binomial pdf p (k; p, r) = k+r−1 (1 − p)kpr, find the maximum likelihood k estimator for p if r is know

Volgvan

Answer:

$\hat p = \frac{r}{\bar x +r}$

Step-by-step explanation:

A negative binomial random variable "is the number X of repeated trials to produce r successes in a negative binomial experiment. The probability distribution of a negative binomial random variable is called a negative binomial distribution, this distribution is known as the Pascal distribution".

And the probability mass function is given by:

$P(X=x) = (x+r-1 C k)p^r (1-p)^{x}$

Where r represent the number successes after the k failures and p is the probability of a success on any given trial.

Solution to the problem

For this case the likehoof function is given by:

$L(\theta , x_i) = \prod_{i=1}^n f(\theta ,x_i)$

If we replace the mass function we got:

$L(p, x_i) = \prod_{i=1}^n (x_i +r-1 C k) p^r (1-p)^{x_i}$

When we take the derivate of the likehood function we got:

$l(p,x_i) = \sum_{i=1}^n [log (x_i +r-1 C k) + r log(p) + x_i log(1-p)]$

And in order to estimate the likehood estimator for p we need to take the derivate from the last expression and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\frac{x_i}{1-p}$

And we can separete the sum and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\sum_{i=1}^n \frac{x_i}{1-p}$

Now we need to find the critical point setting equal to zero this derivate and we got:

$\frac{dl(p,x_i)}{dp} = \sum_{i=1}^n \frac{r}{p} -\sum_{i=1}^n \frac{x_i}{1-p}=0$

$\sum_{i=1}^n \frac{r}{p} =\sum_{i=1}^n \frac{x_i}{1-p}$

For the left and right part of the expression we just have this using the properties for a sum and taking in count that p is a fixed value:

$\frac{nr}{p}= \frac{\sum_{i=1}^n x_i}{1-p}$

Now we need to solve the value of $\hat p$ from the last equation like this:

$nr(1-p) = p \sum_{i=1}^n x_i$

$nr -nrp =p \sum_{i=1}^n x_i$

$p \sum_{i=1}^n x_i +nrp = nr$

$p[\sum_{i=1}^n x_i +nr]= nr$

And if we solve for $\hat p$ we got:

$\hat p = \frac{nr}{\sum_{i=1}^n x_i +nr}$

And if we divide numerator and denominator by n we got:

$\hat p = \frac{r}{\bar x +r}$

Since $\bar x = \frac{\sum_{i=1}^n x_i}{n}$

4 0

3 years ago

The volume of a rectangular box is (x3 - 7x2 - 9x + 63) cubic units. Determine the dimensions of the rectangular box by factorin

Shalnov [3]

Hello,
well done.
As x^3-7x²-9x+63=(x-3)(x+3)(x-7) we must have x>3 and x>-3 and x>7 thus x>7

Explanations:
x^3-7x²-9x+63=x^3-9x+(-7x²+63)=x(x²-9)-7(x²-9)=(x²-9)(x-7)=(x+3)(x-3)(x-7)

6 0

3 years ago

What is the best approximation of the surface area of this right cone?

inn [45]

$\bf \textit{total surface area of a cone}\\\\
s=\pi r\sqrt{r^2+h^2}+\pi r^2\quad 
\begin{cases}
r=radius\\
h=height\\
-----\\
r=12\\
h=9
\end{cases}
\\\\\\
s=\pi (12)\sqrt{12^2+9^2}+\pi (12^2)\implies s=12\pi \sqrt{225}+144\pi 
\\\\\\
s=12\pi (15)+144\pi \implies s=180\pi +144\pi \implies s=324\pi$

8 0

2 years ago