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3 years ago

Explain why it does not matter what letter or symbol is used to find and unknown number?

1 answer:

8 0

It dose not matter what letter or symbol to find the unknown number because you are only using something to represent that number.

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On a multiple choice test of 13 questions, each question has four (4) possible answers, one of which is correct. For students wh

xeze [42]

Answer:

i. $E(X) = 3.25$

ii. $\sqrt{V(X)} = 1.56$

Step-by-step explanation:

For each answer, there are only two possible outcomes. Either it is correct, or it is not. The probability of an answer being correct is independent of other answers. So we use the binomial probability distribution to solve this problem.

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

In this problem, we have that:

Each question has four options, one of which is correct. So the probability of getting each answer correct is $p = \frac{1}{4} = 0.25$

There are 13 questions, so $n = 13$

i. The mean of the random variable X

$E(X) = np = 13*0.25 = 3.25$

ii. The standard deviation of the random variable X

$\sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{13*0.25*0.75} = 1.56$

3 0

3 years ago

A penguin walks 10 feet in 6 seconds, so how long does it take for a penguin to walk 45 feet ?? Plz help me its due in a couple

Nata [24]

Answer: The penguin would walk 45 feet in around 27 seconds.

Step-by-step explanation: 10 ft = 6 sec, 20ft = 12sec, 30ft = 18 sec, 40 ft = 24 sec, 5 ft = 3 sec

6 0

3 years ago

The diameter of a circle is 26 cm. Find its area to the nearest whole number.

fomenos

Area= pi x r^2
= pi x 13^2
=pi x 169
= 530.929
= to the nearest whole number 531

4 0

2 years ago

Read 2 more answers

Is 3ft: 8 sec and 5ft:11 sec equal?

weqwewe [10]

Answer: No they are not equal.

Step-by-step explanation:

6 0

3 years ago

Read 2 more answers

Find the center,vertices,foci,and asymptotes of the hyperbola.

bogdanovich [222]

Answer:

The center is (8 , -9)

The vertices are (11 , -9) and (5 , -9)

The foci are (8 , -9 + √58) and (8 , -9 - √58)

The equations of the asymptotes are y = 3/7(x − 8) - 9 , y = -3/7 (x − 8) - 9

Step-by-step explanation:

- The standard form of the equation of a hyperbola with

center (h , k) and transverse axis parallel to the y-axis is

(y - k)²/a² - (x - h)²/b² = 1

- The length of the transverse axis is 2 a

- The coordinates of the vertices are ( h ± a , k )

- The length of the conjugate axis is 2 b

- The coordinates of the co-vertices are ( h , k ± b )

- The coordinates of the foci are (h , k ± c), where c² = a² + b²

- The equations of the asymptotes are y = ± a/b (x − h) + k

* Now lets solve the problem

∵ (y + 9)²/9 - (x - 8)²/49 = 1

∴ h = 8 and k = -9

∴ a² = 9 ⇒ a = ± 3

∴ b² = 49 ⇒ b = ± 7

∵ c² = a² + b²

∴ c² = 9 + 49 = 58

∴ c = ± √58

∵ The center is (h , k)

∴ The center is (8 , -9)

∵ The coordinates of the vertices are ( h ± a , k )

∴ The vertices are (8 + 3 , -9) and (8 - 3 , -9)

∴ The vertices are (11 , -9) and (5 , -9)

∵ The coordinates of the foci are (h , k ± c)

∴ The foci are (8 , -9 + √58) and (8 , -9 - √58)

∵ The equations of the asymptotes are y = ± a/b (x − h) + k

∴ The equations of the asymptotes are y = 3/7 (x - 8) - 9 and

y = -3/7 (x − 8) - 9

7 0

3 years ago

Read 2 more answers