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2 years ago

13

A history test has 30 questions. A student answers 90% of the questions correctly. How many questions did the student get correc

t.

1 answer:

algol132 years ago

7 0

Answer:

27 questions

Step-by-step explanation:

Hope this helps!

You might be interested in

How do i solve that question?

yawa3891 [41]

a) The solution of this <em>ordinary</em> differential equation is $y =\sqrt[3]{-\frac{2}{\frac{3\cdot t}{8}-\frac{\sin 2t}{4}+\frac{\sin 4t}{32}-2 } }$ .

b) The integrating factor for the <em>ordinary</em> differential equation is $-\frac{1}{x}$ .

The <em>particular</em> solution of the <em>ordinary</em> differential equation is $y = \frac{x^{3}}{2}+x^{2}-\frac{5}{2}$ .

<h3>How to solve ordinary differential equations</h3>

a) In this case we need to separate each variable ( $y, t$ ) in each side of the identity:

$6\cdot \frac{dy}{dt} = y^{4}\cdot \sin^{4} t$ (1)

$6\int {\frac{dy}{y^{4}} } = \int {\sin^{4}t} \, dt + C$

Where $C$ is the integration constant.

By table of integrals we find the solution for each integral:

$-\frac{2}{y^{3}} = \frac{3\cdot t}{8}-\frac{\sin 2t}{4}+\frac{\sin 4t}{32} + C$

If we know that $x = 0$ and $y = 1$ <em>, </em>then the integration constant is $C = -2$ .

The solution of this <em>ordinary</em> differential equation is $y =\sqrt[3]{-\frac{2}{\frac{3\cdot t}{8}-\frac{\sin 2t}{4}+\frac{\sin 4t}{32}-2 } }$ . $\blacksquare$

b) In this case we need to solve a first order ordinary differential equation of the following form:

$\frac{dy}{dx} + p(x) \cdot y = q(x)$ (2)

Where:

$p(x)$ - Integrating factor
$q(x)$ - Particular function

Hence, the ordinary differential equation is equivalent to this form:

$\frac{dy}{dx} -\frac{1}{x}\cdot y = x^{2}+\frac{1}{x}$ (3)

The integrating factor for the <em>ordinary</em> differential equation is $-\frac{1}{x}$ . $\blacksquare$

The solution for (2) is presented below:

$y = e^{-\int {p(x)} \, dx }\cdot \int {e^{\int {p(x)} \, dx }}\cdot q(x) \, dx + C$ (4)

Where $C$ is the integration constant.

If we know that $p(x) = -\frac{1}{x}$ and $q(x) = x^{2} + \frac{1}{x}$ , then the solution of the ordinary differential equation is:

$y = x \int {x^{-1}\cdot \left(x^{2}+\frac{1}{x} \right)} \, dx + C$

$y = x\int {x} \, dx + x\int\, dx + C$

$y = \frac{x^{3}}{2}+x^{2}+C$

If we know that $x = 1$ and $y = -1$ , then the particular solution is:

$y = \frac{x^{3}}{2}+x^{2}-\frac{5}{2}$

The <em>particular</em> solution of the <em>ordinary</em> differential equation is $y = \frac{x^{3}}{2}+x^{2}-\frac{5}{2}$ . $\blacksquare$

To learn more on ordinary differential equations, we kindly invite to check this verified question: brainly.com/question/25731911

3 0

2 years ago

Nina has $5 bills and $10 bills in her wallet. she has a total of 7 bills with a value of $55. how many of each type of bill doe

oee [108]

The answer is 3 fives and 4 tens

7 0

3 years ago

Please help on this question, I will really appreciate it. I will definitely give brainliest to the answer whom gives the full P

alukav5142 [94]

Answer and step-by-step explanation:

Here is the proof!

UR II ST - Given
m<USR = m<SUT - Alternate interior angles
m<R = m<T = 90º - Given
US = US - Reflexive property
Triangle RSU = Triangle TUS - AAS {2,3,4}

Hope this helps!!

7 0

3 years ago

Read 2 more answers

5 + 7x = 4x + 8 What is it?

DaniilM [7]

Answer:

X=1

Hope that helps

7 0

3 years ago

A boat rental company offers two different rental packages. The first rental package costs $45, plus $29.50 per hour. The second

vampirchik [111]

Answer:

1.6 hr

Step-by-step explanation:

1st rental package: y = 29.50x + 45

2nd rental package: y = 0.70x + 90

Set the equation equal to each other;

29.50x + 45 = 0.70x + 90

Subtract 0.70x from both sides;

28.8x + 45 = 90

Subtract 45 from both sides;

28.8x = 45

Divide both sides by 28.8

x = 1.5625 ≈ 1.6

8 0

2 years ago