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3 years ago

Q.16 please With steps

Mathematics

1 answer:

blsea [12.9K]3 years ago

8 0

The equations

$2x^2+9x-5=0$

and

$2\left(t-\dfrac12\right)^2+9\left(t-\dfrac12\right)-5=0$

are really the same, we're just setting $x=t-\dfrac12$ , or $t=x+\dfrac12$ .

$2x^2+9x-5=(2x-1)(x+5)=0\implies x=\dfrac12,x=-5$

So we get

$t=\dfrac12+\dfrac12=1,t=-5+\dfrac12=-\dfrac92$

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In Ms. Perron's class, 75% of the studnetw are doys. There are 18boys in the class. What is the totla numder of students in Ms.

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Your answer should be 24

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3 years ago

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DaniilM [7]

Answer:

its is 50 i am sure of it

Step-by-step explanation:

because 50 is the middle and it is directly on the middle also i have the same school program and i pased that test

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3 years ago

f) The life of a power transmission tower is exponentially distributed, with mean life 25 years. If three towers, operated indep

Step2247 [10]

Answer:

15.24% probability that at least 2 will still stand after 35 years

Step-by-step explanation:

To solve this question, we need to understand the binomial distribution and the exponential distribution.

Binomial probability distribution

The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

In which $C_{n,x}$ is the number of different combinations of x objects from a set of n elements, given by the following formula.

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

And p is the probability of X happening.

Exponential distribution:

The exponential probability distribution, with mean m, is described by the following equation:

$f(x) = \mu e^{-\mu x}$

In which $\mu = \frac{1}{m}$ is the decay parameter.

The probability that x is lower or equal to a is given by:

$P(X \leq x) = \int\limits^a_0 {f(x)} \, dx$

Which has the following solution:

$P(X \leq x) = 1 - e^{-\mu x}$

The probability of finding a value higher than x is:

$P(X > x) = 1 - P(X \leq x) = 1 - (1 - e^{-\mu x}) = e^{-\mu x}$

Probability of a single tower being standing after 35 years:

Single tower, so exponential.

Mean of 25 years, so $m = 25, \mu = \frac{1}{25} = 0.04$

We have to find $P(X > 35)$

$P(X > 35) = 1 - P(X \leq x) = 1 - (1 - e^{-\mu x}) = e^{-0.04*35} = 0.2466$

What is the probability that at least 2 will still stand after 35 years?

Now binomial.

Each tower has a 0.2466 probability of being standing after 35 years, so $p = 0.2466$

3 towers, so $n = 3$

We have to find:

$P(X \geq 2) = P(X = 2) + P(X = 3)$

In which

$P(X = x) = C_{n,x}.p^{x}.(1-p)^{n-x}$

$P(X = 2) = C_{3,2}.(0.2466)^{2}.(0.7534)^{1} = 0.1374$

$P(X = 3) = C_{3,3}.(0.2466)^{3}.(0.7534)^{0} = 0.0150$

$P(X \geq 2) = P(X = 2) + P(X = 3) = 0.1374 + 0.0150 = 0.1524$

15.24% probability that at least 2 will still stand after 35 years

4 0

3 years ago

An office building casts a 90 foot shadow. At the same time of day, a 5 foot woman standing near the building casts an 8 foot sh

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Make a ratio:

Make sure shadow is in same location on both fractions (either numerator or denominator) 

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Cross multiply:

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That makes sense, too, because the woman's shadow is taller than she is, but is less than double her height. The building shadow is taller than the building, but it's less than double the height of the building.

I hope my answer has come to your help. Thank you for posting your question here in Brainly.

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3 years ago

Read 2 more answers

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nordsb [41]

Answer:

Step-by-step explanation:

For it to be a function, every x value must have 1 unique y value ONLY.

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In option B, you can see that the x value of 0 has 2 y values, 0 & -4. Moreover, the x value of 4 also has 2 y values, 2 & -2. So it's not a function.

In option C, you can see that the x value of -2 has 2 y values, 4 & -4. This is not a function as well.

In option D, each x value has a unique y value that are different. So this is a function.

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2 years ago