Evaluate -8(x - 3y) when x = -2 and y= -4
1 answer:
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Answer:
The labor fee is $14.25, each quart of oil costs $2.25.
Step-by-step explanation:
Let $x be thee price of each quart of oil and $y be a flat fee for labor.
1. If the oil change for one car required 5 quarts of oil, then these 5 quarts cost $5x and together with a flat fee for labor it cost $25.50. Thus,
5x+y=25.50.
2. If the oil change for another car required 7 quarts of oil, then these 7 quarts cost $7x and together with a flat fee for labor it cost $30.00. Thus,
7x+y=30.00.
3. Subtract from the second equation the first one, then
Substitute it into the first equation:
The labor fee is $14.25, each quart of oil costs $2.25.
Answer:
B) Mean
Step-by-step explanation:
Standard Deviation is the measure of the amount of variation or dispersion of a set of values. Standard Deviation is represented by lower case Greek alphabet sigma σ. Standard Deviation is the square root of variance. Variance is the average of the squared differences or variation or dispersion from the Mean. Therefore, to compute standard deviation, the mean of the given data must be known.
Standard Deviation, σ =
σ = ∑
where
are the values of the sample observed,
X is the mean value of these observations, and
N is the number of observations in the sample.