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nadezda [96]
3 years ago
9

A test consists of 100 multiple choice questions, each with five possible answers, only one of which is correct. Find the mean a

nd the standard deviation of the number of correct answers. mean: 20; standard deviation: 4 mean: 20; standard deviation: 4.47 mean: 50; standard deviation: 7.70 mean: 50; standard deviation: 4
Mathematics
1 answer:
TEA [102]3 years ago
6 0

Answer:  Mean = 20 and standard deviation = 4

Step-by-step explanation:

Let x represents the success of getting the correct answer.

Here, the total number of trials(n) = 100

The probability of getting the correct answer, p = 1/5

Thus, the mean of the number of correct answer,

\mu_x= np

\mu_x= 100\times 1/5

\mu_x= 20

Now, the standard deviation, \sigma_x= \sqrt{n\times p\times (1-p)}

\sigma_x= \sqrt{100\times 1/5\times 4/5}

\sigma_x= \sqrt{16}

\sigma_x= 4

Thus, First option is correct.



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A person must be at least 4 feet tall to ride an amusement park ride. Which inequality represents the height, h, of a person who
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Answer:

4≥x

Step-by-step explanation:

The person has to be at least four feet (=) or he can be higher (>).

3 0
3 years ago
What is the area of the sector of the circle below, if the radius is 5 m. and the central angle < AOB measures 88 °. (round a
MariettaO [177]

Answer:

b 19.2

Step-by-step explanation:

a = \pir^{2} for a circle.  We do not want to find the area for a whole circle.  We only want to find the area for part of a circle.  a hole circle is 360 degrees.

a = \frac{88}{360}\pir^{2}

a = \frac{88}{360}\pi(5^{2})

a = 19.2 rounded.

8 0
1 year ago
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How to solve 4n²-3n-7=0
almond37 [142]
4n^2-3n-7=0\\ \\ a=4, \ \ b=-3 \ \ c=-7\\ \\ \Delta = b^{2}-4ac = (-3)^{2}-4*4* (-7)= 9+112=121

x_{1}=\frac{-b-\sqrt{\Delta }}{2a} =\frac{ 3-\sqrt{ 121}}{2*4}=\frac{ 3-11}{8}= \frac{-8 }{ 8}=-1 \\ \\x_{2}=\frac{-b+\sqrt{\Delta }}{2a} =\frac{ 3+\sqrt{ 121}}{2*4}=\frac{ 3+11}{8}= \frac{14 }{ 8}= \frac{7}{4}=1\frac{3}{4}


4 0
3 years ago
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Complete the slope equation of the line through 2,3 and 7, 4 <br><br> Y-4=
In-s [12.5K]

Answer:

The slope equation of the line AB is (y -4) = \frac{1}{5} (x-7)

Step-by-step explanation:

Here, the given points are A (2, 3) and B (7,4).

Now, slope of any line is given as :

m = \frac{y_2 - y_1}{x_2 - x_1}

or, m = \frac{4 -3}{7-2}   = \frac{1}{5}

Hence, the slope of the line AB is (1/5)

Now , A POINT SLOPE FORM of an equation is

(y - y0)  = m (x - x0) ; (x0, y0)  is any arbitrary point on line.

Hence, the equation of line AB with slope (1/5 )  and point (7,4) is given as:

(y  -4 ) = \frac{1}{5}  ( x - 7)

or, 5y  - 20 = x -7

⇒  x - 57  + 13 = 0  ( SIMPLIFIED FORM of equation)

Hence, the slope equation of the line AB is (y -4) = \frac{1}{5} (x-7)

3 0
2 years ago
Write the follow ratio is lowest terms, 49:21
Alik [6]
Looking at 49 and 21, you immediately know that 7 can be divided out of both.

49:21
=49/7:21/7
=7:3

7:3 is the answer.

Hope this helps!

5 0
3 years ago
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