Solved on Sep 15, 2023

Seat belt usage affects deaths. For every 1% increase in usage, deaths decrease by 280. Find the slope bb and predict deaths if (i) 0%, (ii) 74%, (iii) 100% wear seat belts, given yy-intercept is 28,910.
a. The slope is b=280b = -280.

STEP 1

Assumptions1. The initial number of deaths due to not wearing seat belts is9000. . The number of deaths decreases by280 for every1 percentage point increase in seat belt usage.
3. Let y^\hat{y} be the predicted number of deaths in a year and xx be the percentage of people who wear seat belts.
4. The equation for the predicted number of deaths is y^=a+bx\hat{y}=a+b x.
5. The yy-intercept aa is28,910.

STEP 2

First, we need to find the slope bb of the equation. The slope represents the change in y^\hat{y} (the predicted number of deaths) for a1 unit change in xx (the percentage of people who wear seat belts). According to the problem, the number of deaths decreases by280 for every1 percentage point increase in seat belt usage. Therefore, the slope bb is -280.
b=280b = -280

STEP 3

Now, we can use the equation y^=a+bx\hat{y}=a+b x to predict the number of deaths in a year if no one wears seat belts. This corresponds to x=0x=0. Plugging in the values for aa and xx givesy^=a+b0\hat{y} = a + b \cdot0

STEP 4

Calculate the predicted number of deaths when no one wears seat belts.
y^=28910+(280)0=28910\hat{y} =28910 + (-280) \cdot0 =28910

STEP 5

Next, we can use the equation y^=a+bx\hat{y}=a+b x to predict the number of deaths in a year if74% of people wear seat belts. This corresponds to x=74x=74. Plugging in the values for aa, bb, and xx givesy^=a+b74\hat{y} = a + b \cdot74

STEP 6

Calculate the predicted number of deaths when74% of people wear seat belts.
y^=28910+(280)74=2891020720=8190\hat{y} =28910 + (-280) \cdot74 =28910 -20720 =8190

STEP 7

Finally, we can use the equation y^=a+bx\hat{y}=a+b x to predict the number of deaths in a year if100% of people wear seat belts. This corresponds to x=100x=100. Plugging in the values for aa, bb, and xx givesy^=a+b100\hat{y} = a + b \cdot100

STEP 8

Calculate the predicted number of deaths when100% of people wear seat belts.
y^=28910+(280)100=2891028000=910\hat{y} =28910 + (-280) \cdot100 =28910 -28000 =910a. The slope is b=280b=-280. b. The predicted number of deaths in a year is i.28,910 if no one wears seat belts. ii.8,190 if74% of people wear seat belts. iii.910 if100% of people wear seat belts.

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