<img src="https://tex.z-dn.net/?f=0.7x%5E%7B2%7D%20%20-%204.3x%20%2B%203.9%20" id="TexFormula1" title="0.7x^{2}

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Rainbow [258]

3 years ago

alt="0.7x^{2} - 4.3x + 3.9 " align="absmiddle" class="latex-formula">

Mathematics

1 answer:

Ostrovityanka [42]3 years ago

4 0

Use the quadratic formula to get
x= -11.24188336 or -15.17240236

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There are 42 students in an elementary statistics class. On the basis of years of experience, the instructor knows that the time

harkovskaia [24]

Answer:

A) 0.99413

B) 0.00022

Step-by-step explanation:

A) First of all let's find the total grading time from 6:50 P.M to 11:00 P.M.:

Total grading time; X = 11:00 - 6:50 = 4hours 10minutes = 250 minutes

Now since we are given an expected value of 5 minutes, the mean grading time for the whole population would be:

μ = n*μ_s ample = 42 × 5 = 210 minutes

While the standard deviation for the population would be:

σ = √nσ_sample = √(42 × 6) = 15.8745 minutes

To find the z-score, we will use the formula;

z = (x - μ)/σ

Thus;

z = (250 - 210)/15.8745

z = 2.52

From the z-distribution table attached, we have;

P(Z < 2.52) ≈ 0.99413

B) solving this is almost the same as in A above, the only difference is an additional 10 minutes to the time.

Thus, total time is now 250 + 10 = 260 minutes

Similar to the z-formula in A above, we have;

z = (260 - 210)/15.8745

z = 3.15

P(Z > 3.15) = 0.00022

5 0

3 years ago

Tic is an isosceles triangle with a vertex angle I. if the angle of I is 70. find the measure of t.

Colt1911 [192]

Angles of a triangle = 180 degrees
T + C = 110 degrees, and T=C (according to the definition of an isosceles triangle).
measure of T is 110/2 which equals 55 degrees

3 0

4 years ago

Read 2 more answers

Which shows a set of figures that always possesses all these attributes?

Scilla [17]

Answer:

Step-by-step explanation:

Four right angles eliminates trapezoids.

Four right angles also eliminates any triangle

General quadrilaterals should be eliminated by the 4 right angles. If they have 4 right angles, the figure is not a general quadrilateral.

The answer is rectangles and squares.

5 0

3 years ago

Which expression represents the number 2i4−5i3+3i2+−81‾‾‾‾√ rewritten in a+bi form?

vichka [17]

Answer:

The expression $-1+14i$ represents the number $2i^4-5i^3+3i^2+\sqrt{-81}$ rewritten in a+bi form.

Step-by-step explanation:

The value of $i$ is $i=\sqrt{-1}[tex] or [tex]i^{2}=-1[\tex].Now [tex]i^{4}$ in term of $i^{2}[\tex] can be written as, [tex]i^{4}=i^{2}\times i^{2}$

Substituting the value,

$i^{4}=\left(-1\right)\times \left(-1\right)$

Product of two negative numbers is always positive.

$\therefore i^{4}=1$

Now $i^{3}$ in term of $i^{2}[\tex] can be written as, [tex]i^{3}=i^{2}\times i$

Substituting the value,

$i^{3}=\left(-1\right)\times i$

Product of one negative and one positive numbers is always negative.

$\therefore i^{3}=-i$

Now $\sqrt{-81}$ can be written as follows,

$\sqrt{-81}=\sqrt{\left(81\right)\times\left(-1\right)}$

Applying radical multiplication rule,

$\sqrt{ab}={\sqrt{a}}\sqrt{b}$

$\sqrt{\left(81\right)\times\left(-1\right)}={\sqrt{81}}\sqrt{-1}$

Now, $\sqrt{\left(81\right)=9$ and $\sqrt{-1}}=i$

$\therefore \sqrt{\left(81\right)\times\left(-1\right)}=9i$

Now substituting the above values in given expression,

$2i^4-5i^3+3i^2+\sqrt{-81}=2\left(1\right)-5\left(-i\right)+3\left(-1\right)+9i$

Simplifying,

$2+5i-3+9i$

Collecting similar terms,

$2-3+5i+9i$

Combining similar terms,

$-1+14i$

The above expression is in the form of a+bi which is the required expression.

Hence, option number 4 is correct.

5 0

3 years ago

HELP ME PLEASEEEEEEEEEEEE

olga nikolaevna [1]

Answer:

Step-by-step explanation:

The first number is always x-coordinate. And amongst all only J and L has positive x-coordinates. With J y-coordinate is also positive so it should be L

5 0

3 years ago