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3 years ago

Select all the expressions that are equivalent to 4b:

Mathematics

1 answer:

Alinara [238K]3 years ago

8 0

Answer:

No. 1 , 3 and 5 is correct.

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Which answer is the approximate standard deviation of the data set?

Ierofanga [76]

Answer: A. 6.5

Step-by-step explanation:

Here, the given set = { 15, 19 3, 12, 17, 2, 2, 8}

Mean, $\overline{ x} = \frac{15+19+3+12+17+2+2+8}{8} = \frac{78}{8} = 9.75$

Number of elements, n = 8

$\frac{\sum (|x-\overline{x}|)^2}{n}=42.4375$

Thus, the standard deviation, $\sigma =\frac{\sqrt{\sum(|x-\overline{x}|)^2} }{n}=\sqrt{\frac{339.5}{8}}=\sqrt{42.4375} = 6.51440711\approx 6.5$

⇒ Option A is correct.

4 0

4 years ago

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The box plot and histogram show the number of minutes sixth-grade students spent reading the previous night.Which statements bes

Finger [1]

Answer:

2,3,and 5

Step-by-step explanation:

took the test

5 0

4 years ago

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PLEASE HELP ME WITH THIS !!

Anon25 [30]

3x3.5=10.5ft since 1 cm=3.5ft, and the car is 3cm

8 0

3 years ago

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Find the exact value of the expression.<br> tan( sin−1 (2/3)− cos−1(1/7))

Sonja [21]

Answer:

$\tan(a-b)=\frac{2\sqrt{5}-20\sqrt{3}}{5+8\sqrt{15}}$

Step-by-step explanation:

I'm going to use the following identity to help with the difference inside the tangent function there:

$\tan(a-b)=\frac{\tan(a)-\tan(b)}{1+\tan(a)\tan(b)}$

Let $a=\sin^{-1}(\frac{2}{3})$ .

With some restriction on $a$ this means:

$\sin(a)=\frac{2}{3}$

We need to find $\tan(a)$ .

$\sin^2(a)+\cos^2(a)=1$ is a Pythagorean Identity I will use to find the cosine value and then I will use that the tangent function is the ratio of sine to cosine.

$(\frac{2}{3})^2+\cos^2(a)=1$

$\frac{4}{9}+\cos^2(a)=1$

Subtract 4/9 on both sides:

$\cos^2(a)=\frac{5}{9}$

Take the square root of both sides:

$\cos(a)=\pm \sqrt{\frac{5}{9}}$

$\cos(a)=\pm \frac{\sqrt{5}}{3}$

The cosine value is positive because $a$ is a number between $-\frac{\pi}{2}$ and $\frac{\pi}{2}$ because that is the restriction on sine inverse.

So we have $\cos(a)=\frac{\sqrt{5}}{3}$ .

This means that $\tan(a)=\frac{\frac{2}{3}}{\frac{\sqrt{5}}{3}}$ .

Multiplying numerator and denominator by 3 gives us:

$\tan(a)=\frac{2}{\sqrt{5}}$

Rationalizing the denominator by multiplying top and bottom by square root of 5 gives us:

$\tan(a)=\frac{2\sqrt{5}}{5}$

Let's continue on to letting $b=\cos^{-1}(\frac{1}{7})$ .

Let's go ahead and say what the restrictions on $b$ are.

$b$ is a number in between 0 and $\pi$ .

So anyways $b=\cos^{-1}(\frac{1}{7})$ implies $\cos(b)=\frac{1}{7}$ .

Let's use the Pythagorean Identity again I mentioned from before to find the sine value of $b$ .

$\cos^2(b)+\sin^2(b)=1$

$(\frac{1}{7})^2+\sin^2(b)=1$

$\frac{1}{49}+\sin^2(b)=1$

Subtract 1/49 on both sides:

$\sin^2(b)=\frac{48}{49}$

Take the square root of both sides:

$\sin(b)=\pm \sqrt{\frac{48}{49}$

$\sin(b)=\pm \frac{\sqrt{48}}{7}$

$\sin(b)=\pm \frac{\sqrt{16}\sqrt{3}}{7}$

$\sin(b)=\pm \frac{4\sqrt{3}}{7}$

So since $b$ is a number between $0$ and $\pi$ , then sine of this value is positive.

This implies:

$\sin(b)=\frac{4\sqrt{3}}{7}$

So $\tan(b)=\frac{\sin(b)}{\cos(b)}=\frac{\frac{4\sqrt{3}}{7}}{\frac{1}{7}}$ .

Multiplying both top and bottom by 7 gives:

$\frac{4\sqrt{3}}{1}= 4\sqrt{3}$ .

Let's put everything back into the first mentioned identity.

$\tan(a-b)=\frac{\tan(a)-\tan(b)}{1+\tan(a)\tan(b)}$

$\tan(a-b)=\frac{\frac{2\sqrt{5}}{5}-4\sqrt{3}}{1+\frac{2\sqrt{5}}{5}\cdot 4\sqrt{3}}$

Let's clear the mini-fractions by multiply top and bottom by the least common multiple of the denominators of these mini-fractions. That is, we are multiplying top and bottom by 5:

$\tan(a-b)=\frac{2 \sqrt{5}-20\sqrt{3}}{5+2\sqrt{5}\cdot 4\sqrt{3}}$

$\tan(a-b)=\frac{2\sqrt{5}-20\sqrt{3}}{5+8\sqrt{15}}$

4 0

3 years ago

What is the difference of the ones and the tenth digit of the pi?

antiseptic1488 [7]

Answer:

Step-by-step explanation:

The value of pi is 22/7

Expressing as a decimal, the first ten digits of pi is 3.1415926535

The value in the tenth digit of the pi is 5 (tenth value after the decimal point)

The value of the ones is 3(The value before the decimal point)

The difference between both values = 5 - 3

The difference between both values = 2

Hence the difference of the ones and the tenth digit of the pi is 2

8 0

3 years ago