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Solnce55 [7]
3 years ago
8

Your teacher is giving you a test worth 100 points containing 40 questions. There are two point and to

Mathematics
1 answer:
lisov135 [29]3 years ago
8 0

Answer:

There are <u>30</u> two point questions and <u>10</u> four point questions  on the test.

Step-by-step explanation:

Given:

Your teacher is giving you a test worth 100 points containing 40 questions. There are two point and four point questions on the test.

Now, to find number of each type of question are on the test.

Let the two point questions be x.

And let the four point questions be y.

So, total questions:

x+y=40..........( 1 )

⇒ y=40-x.

Now, total number of points of the questions on the test:

2x+4y=100.

<em>Substituting the value of y:</em>

⇒ 2x+4(40-x)=100

⇒ 2x+160-4x=100

⇒ 160-2x=100

<em>Adding both sides by 2x we get:</em>

⇒ 160=100+2x

<em>Subtracting both sides by 100 we get:</em>

⇒ 60=2x

<em>Dividing both sides by 2 we get:</em>

⇒ 30=x

⇒ x=30.

The number of two point questions = 30.

Putting the value of x in the equation ( 1 ) we get:

30+y=40.

<em>Subtracting both sides by 30 we get:</em>

⇒ y=10.

The number of four point questions = 10.

Therefore, there are 30 two point questions and 10 four point questions on the test.

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The prices of all college textbooks follow a bell-shaped distribution with a mean of $113 and a standard deviation of $12. Using
Soloha48 [4]

Step-by-step explanation:

In statistics, the empirical rule states that for a normally distributed random variable,

  • 68.27% of the data lies within one standard deviation of the mean.

  • 95.45% of the data lies within two standard deviations of the mean.

  • 99.73% of the data lies within three standard deviations of the mean.

In mathematical notation, as shown in the figure below (for a standard normal distribution), the empirical rule is described as

                             \Phi(\mu \ - \ \sigma \ \leq X \ \leq \mu \ + \ \sigma) \ = \ 0.6827 \qquad (4 \ \text{s.f.}) \\ \\ \\ \Phi(\mu \ - \ 2\sigma \ \leq X \ \leq \mu \ + \ 2\sigma) \ = \ 0.9545 \qquad (4 \ \text{s.f.}) \\ \\ \\ \Phi}(\mu \ - \ 3\sigma \ \leq X \ \leq \mu \ + \ 3\sigma) \ = \ 0.9973 \qquad (4 \ \text{s.f.})

where the symbol \Phi (the uppercase greek alphabet phi) is the cumulative density function of the normal distribution, \mu is the mean and \sigma is the standard deviation of the normal distribution defined as N(\mu, \ \sigma).

According to the empirical rule stated above, the interval that contains the prices of 99.7% of college textbooks for a normal distribution N(113, \ 12),

                \Phi(113 \ - \ 3 \ \times \ 12 \ \leq \ X \ \leq \ 113 \ + \ 3 \ \times \ 12) \ = \ 0.9973 \\ \\ \\ \-\hspace{1.75cm} \Phi(113 \ - \ 36 \ \leq \ X \ \leq \ 113 \ + \ 36) \ = \ 0.9973 \\ \\ \\ \-\hspace{3.95cm} \Phi(77 \ \leq \ X \ \leq \ 149) \ = \ 0.9973

Therefore, the price of 99.7% of college textbooks falls inclusively between $77 and $149.

5 0
2 years ago
Help.... and thanks
Archy [21]

Answer:

π

Step-by-step explanation:

The *period* of a function is the length it takes before it repeats. Usually, the period of the sine function is 2π; it takes a full rotation around the unit circle for it to repeat. When we replace the input x with -2x, this does a few things:

- Changes the rotation direction

- Makes the rotation go twice as fast

If we rotate around the unit circle twice as fast, it’ll take us half of 2π, or just π to complete a cycle.

6 0
3 years ago
3 - (2x - 5) &lt; -4(x + 2)​
DIA [1.3K]

Answer:

x < -8

Step-by-step explanation:

3 - (2x - 5) < -4(x + 2)​

-2x + 8 < -4x - 8

-2x < -4x - 16

2x < -16

x < -8

Best of Luck!

7 0
3 years ago
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Likurg_2 [28]

-1 - 2 = -3

R = -3

-4 + 1 = -3

S = -3

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6 0
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C represents Celsius and F represent Fahrenheit.

Hope this helps!
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