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Answer:
Step-by-step explanation:
Please consider the complete question.
Sebastian swan laps every day in the community swimming pool. He swam 45 minutes each day, 5 days each week, for 12 weeks. In that time, he swam 1800 laps. What was his average rate in laps per hour?
Let us convert time taken into hours as:
1 hour = 60 minutes. To convert minutes into hours, we will divide total minutes by 60.
Now, we will divide 1800 by 45 to find average rate in laps per hour as:
Therefore, Sebastian's average rate is 40 laps per hour.
Part A:
x + y = 9
4x + y = 6
To solve this system using substitution, begin by isolating either x or y in the first equation. I'll isolate x.
x + y = 9
x = 9 - y
Substitute this expression (9 - y) into the second equation for x and solve.
4x + y = 6
4(9 - y) + y = 6
36 - 4y + y = 6
36 - 3y = 6
-3y = -30
y = 10
To find x, substitute 10 for y into either of the original equations.
x + y = 9
x + 10 = 9
x = -1
Finally, check all work by substituting the x- and y-values into each original equation.
x + y = 9 --> -1 + 10 = 9 --> 9 = 9 --> True
4x + y = 6 --> 4(-1) + 10 = 6 --> -4 + 10 = 6 --> 6 = 6 --> True
The answer for Part A is x = -1 and y = 10; (-1, 10).
Part B:
For graphing, it's easier to get the equations into slope-intercept form. Slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept. To get our equations into slope-intercept form, we must simply isolate y.
x + y = 9
y = 9 - x
y = -x + 9
4x + y = 6
y = 6 - 4x
y = -4x + 6
Now that we have our slope-intercept equations, we can easily graph them, since their slopes and y-intercepts are readily visible.
Let's start with the y-intercepts. They are (0, 9) and (0, 6). You can plot those points on the graph.
Now, the slopes. The slope of the first line is -1, this means it declines. To plot this, start where you plotted the y-intercept, count one unit down, and then one unit to the right, and plot that point. Continue doing that and connect the dots, and you will have plotted the first line. The slope of the second line is -4, so it also declines. For this line, count four units down, and then one to the right and plot that point. Likewise, continue this and connect the coordinates, and you will have your line. (See attachment for graph.)
The lines do indeed intersect at (-1, 10); our answer is verified by graphing.
Answer: b
Explanation:
The line of best fit to a scattergram is obtained in linear regression analysis by minimizing the sum of the squared errors.
For example, in the diagram shown below, there are n data points in the scattergram.
The error for the i-th data point is
.
The coefficients (a and b) for the line of best fit are determined using calculus, to minimize
.
Explanation:
The line of best fit to a scattergram is obtained in linear regression analysis by minimizing the sum of the squared errors.
For example, in the diagram shown below, there are n data points in the scattergram.
The error for the i-th data point is
The coefficients (a and b) for the line of best fit are determined using calculus, to minimize