The decimal is equivalent to 4/5. Answer: The decimal is converted to 4/5 as a fraction.
The average score is 500 points and the standard deviation is 50 points.Mean - 2 SD = 500 - 2 * 50 = 500 - 100 = 400It means that more than 400 on the standardized test is more than: Mean - 2 Standard deviations.For the Normal distribution: 100% - 2.5 % = 97.5% = 0.975.Answer: The probability that student scores more than 400 points is 0.975.
Domain: Set of all real numbersIf you want to express the domain in set-builder notation, then you'd write something like

which is fancy notation to basically say "x is any real number"
If you want to write the domain in interval notation, then you'd write

which is the interval from negative infinity to positive infinity. In other words, the entire real number line.
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The domain is the set of all real numbers because we don't have any restrictions to worry about. There are no division by zero errors. There are no cases where we have to worry about taking the square root of a negative number, or anything similar. Any number can replace x to generate an output for y.
The solution is when they intersect. So to find the answer, set each equation equal to each and solve:
-2x + 3 = x^2 -6x + 3
3 = x^2 -4x + 3
0 = x^2 -4x
0 = x(x-4)
So the solutions are x = 0 and x = 4
Plug in these values into the easier equation to solve for the y's
x = 0 into -2x + 3 gives y = 3
So one solution is (0, 3)
x = 4 into -2x + 3 gives y = -5
So the second solution is (4, -5)