Suppose a gas station monitors how many bags of ice they sell along with the maximum daily temperature for 100 days. A gas stati
on data analyst plots the data in a scatter plot with temperature, in °F, on the horizontal axis and the number of bags of ice sold on the vertical axis. She calculates a linear correlation coefficient of r = 0.9952 . The mean temperature is 84.1259 °F with a standard deviation of 9.6121 °F. The mean number of ice bags sold is 71.1173 with a standard deviation of 30.2413. Determine the slope, b , and the intercept, a , of the least-squares regression line for this dataset, precise to two decimal places.
1 answer:
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Answer:
A. -2sin(x)sin(0.4x)
Step-by-step explanation:
At x=0, the given expression evaluates to zero.
For x near zero, the given expression is slightly negative. You know this because cos(1.4x) decreases faster than cos(0.6x), so their difference will be negative.
Of the answer choices, you can eliminate C and D because they are not zero at x=0. You can eliminate choice B, because it is positive for values of x near zero. The only viable choice is A:
-2sin(x)sin(0.4x)
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Of course, a graphing calculator can help you figure this out. See the attachment. The given expression is plotted using a solid red line; the answer choice A is plotted using blue dots.
