Linear regression line y=2.1x+130 predicts sales based on the money spent on advertising.
Linear regression represents the relationship between two variables. the value of y depends on the value of x.
x represents the dollars spent in advertising and y represents the company sales in dollars.
We need to find out sales y when $150 spends on advertising.
Plug in 150 for x and find out y
y = 2.1 x + 130
y = 2.1 (150) + 130
y= 445
The company expects $445 in sales
Note on how to solve such equation:
This is a quadradic equation. The figure shown is a parabola. This parabola opens downward. Now, this information is not necessary important for this particular situation; however, it needs to be retained for said class or for the near future.
The equation for a quadradic function is: f(x)=x^2+2
when x=-2, y=1
Answer:
ai) 73000 gal/yr
aii) $730 per year
b) 1000 days
Step-by-step explanation:
ai) The water usage per day is ...
(4 showers/day)(10 min/shower)(5 gal/min) = 200 gal/day
Then the usage per year is ...
(200 gal/day)(365 days/yr) = 73,000 gal/yr
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aii) The cost of electricity is the cost of heating half the water usage, so is ...
(0.20 kWh/gal)(1/2)(73,000 gal/yr)($0.10/kWh) = $730/yr
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b) The current daily cost of electricity for heating water is ...
($730/yr)/(365 days/yr) = $2/day
If the cost is cut in half, it will be $1 per day. That means the savings is $1 per day, so it will take 1000 days to recover the $1000 initial cost. (Effectively, the average cost for the first 1000 days is the same as if the water heater had not been replaced.)
Rounding to the nearest ten:
28 → 30
188 → 190
250 → 250
101 → 100
122 → 120
