Find the probability that the senator was in the Democratic party, given that the senator was returning to office.
2 answers:
Answer:
The probability that the senator was in the Democratic party, given that the senator was returning to office is 0.4715.
Step-by-step explanation:
The complete question is:
Sophia made the following two-way table categorizing the US senators in 2015 by their political party and whether or not it was their first term in the senate.
Democratic Republican Independent Total
First Term 11 28 11 50
Returning 33 26 11 70
Total 44 54 22 120
Find the probability that the senator was in the Democratic party, given that the senator was returning to office.
Solution:
The conditional probability of an event <em>A</em> given that another event <em>X</em> has already occurred is given by:
The probability of an event <em>E</em> is given by the ratio of the number of favorable outcomes to the total number of outcomes.
Compute the probability of selecting an US senator who is a Democratic and was returning to office as follows:
Compute the probability of selecting an US senator who was returning to office as follows:
Compute the conditional probability, P (D | R) as follows:
Thus, the probability that the senator was in the Democratic party, given that the senator was returning to office is 0.4715.
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Answer:
{1, (-1±√17)/2}
Step-by-step explanation:
There are formulas for the real and/or complex roots of a cubic, but they are so complicated that they are rarely used. Instead, various other strategies are employed. My favorite is the simplest--let a graphing calculator show you the zeros.
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Descartes observed that the sign changes in the coefficients can tell you the number of real roots. This expression has two sign changes (+-+), so has 0 or 2 positive real roots. If the odd-degree terms have their signs changed, there is only one sign change (-++), so one negative real root.
It can also be informative to add the coefficients in both cases--as is, and with the odd-degree term signs changed. Here, the sum is zero in the first case, so we know immediately that x=1 is a zero of the expression. That is sufficient to help us reduce the problem to finding the zeros of the remaining quadratic factor.
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Using synthetic division (or polynomial long division) to factor out x-1 (after removing the common factor of 4), we find the remaining quadratic factor to be x²+x-4.
The zeros of this quadratic factor can be found using the quadratic formula:
a=1, b=1, c=-4
x = (-b±√(b²-4ac))/(2a) = (-1±√1+16)/2
x = (-1 ±√17)2
The zeros are 1 and (-1±√17)/2.
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The graph shows the zeros of the expression. It also shows the quadratic after dividing out the factor (x-1). The vertex of that quadratic can be used to find the remaining solutions exactly: -0.5 ± √4.25.
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The given expression factors as ...
4(x -1)(x² +x -4)
