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3 years ago

5

A test consists of 490 true or false questions. If the student guesses on each question, what is the standard deviation of the n

umber of correct answers? Round the answer to the nearest hundredth.

1 answer:

monitta3 years ago

3 0

I believe the answer is 1.

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Students heights in inches were obtained as part of a study and a frequency distribution was constructed with the first class ha

polet [3.4K]

The frequency of the second class is 6.

Since the class width is 6 and the lower limit of the first class is 50, this means the first class goes from 50-55. This would put the second class at 56-61. There are 6 data points in this set that would go in the second class.

8 0

3 years ago

Y=-x^2+6x-4<br> Find the Axis of Symmetry and the Vertex, Also solve the whole equation.

Inessa [10]

Answer:

1. <em>Axis of symmetry</em>: x = 3

2. <em>Vertex:</em> (3,5)

3. <em>Solution of the equation</em>:

<u />

x-intercepts:

$(3-\sqrt{5},0) \\\\(3+\sqrt{5},0)$

y-intercept: (0, -4)

Explanation:

<u>1. Equation:</u>

$y=-x^2+6x-4$

<u>2. </u><em><u>Axis of symmetry:</u></em>

That is the equation of a parabola, whose standard form is:

$y=ax^2+bx+c$

Where:

$a=-1;b=6;c=-4$

The axis of symmetry is the vertical line with equation:

$x=-b/2a$

Substitute $a=-1,\text{ and }b=6$

$x=-6/[(2)(-1)]=-6/(-2)=3$

Thus, the axis of symmetry is:

$x=3$

<em><u>3. Vertex</u></em>

<em><u /></em>

The x-coordinate of the vertex is equal to the axys of symmetry, i.e x = 3.

To find the y-xoordinate, substitute this value of x into the equation for y:

$y=-x^2+6x-4\\\\y=-(3)^2+6(3)-4=-9+18-4=5$

Therefore, the vertex is (3, 5)

<u>4. Find the x-intercepts</u>

The x-intercepts are the roots of the equation, which are the points wher y = 0.

$y=-x^2+6x-4=0$

Use the quadratic equation:

$x=\frac{-b\pm \sqrt{b^2-4ac} }{2a} \\\\x=\frac{-6\pm\sqrt{(-6)^2-4(-1)(-4)} }{2(-1)}\\\\x_1=3-\sqrt{5} \\\\x_2=3+\sqrt{5}$

<u>5. Find the y-intercept</u>

<u />

The y-intercet is the value of y when x=0:

$y=-x^2+6x-4\\\\y=-(0)^2+6(0)-4=-4$

7 0

3 years ago

How do we write the difference of a number and 4?

rjkz [21]

Answer:

x-4

Step-by-step explanation:

easy

8 0

3 years ago

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the number of the students of a school was 640 last year and it is 800 by how many percent is the number increased

yuradex [85]

Answer:

The number of students would have increased by 25%.

Step-by-step explanation:

8 0

2 years ago

Read 2 more answers

Whats the answer i need help

julia-pushkina [17]

Answer)3.5
1)minus 17.5-14=3.5
2)14+3.5=17.5
3)keep adding 3.5

6 0

3 years ago