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The equation that has the solution is 3x^2 - 10x + 6 = 0
The solution is given as:
The solution to a quadratic equation is
By comparing both equations, we have:
-b = 5
b^2 - 4ac = 7
2a = 3
Solve for b in -b = 5
b = -5
Solve for a in 2a = 3
a = 1.5
Substitute values for a and b in b^2 - 4ac = 7
(-5)^2 - 4 * 1.5c = 7
Evaluate
25 - 6c = 7
Subtract 25 from both sides
-6c = -18
Divide by - 6
c = 3
So, we have:
a = 1.5
b = -5
c = 3
A quadratic equation is represented as:
ax^2 + bx + c = 0
So, we have:
1.5x^2 - 5x +3 = 0
Multiply through by 2
3x^2 - 10x + 6 = 0
Hence, the equation that has the solution is 3x^2 - 10x + 6 = 0
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Answer:
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
Solution to the problem
Let X the random variable that represent the grades of a population, and for this case we know the distribution for X is given by:
For this case we have two conditions given:
or equivalently
And the best way to solve this problem is using the normal standard distribution and the z score given by:
So we can find a value from the normal standard distribution that accumulates 0.1 and 0.9 of the area in the left, for this case the two values are:
We can verify that P(Z<-1.28) =0.1[/tex] and P(Z<1.28) =0.9[/tex]
And then using the z score we have the following formulas:
(1)
(2)
If we add equations (1) and (2) we got:
We can multiply both sides of the equation by and we got:
And then we can find the standard deviation for example from equation (1) and we got:
So then the answer would be: