Question 65902
The total length (l) of a certain species of snake is related linearly to the tail length (t) of this snake.  Here are the measurements for two snakes of this species.  Snake 1:l=150 mm and t=19 mm; snake 2:l=300 mm and t=40 mm.  Use the ordered pairs (l, t).
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You have two points in the form (l,t): (150,19) and (300,40)
a. Find the linear equation for these data points.
slope=[40-19]/[300-140]=21/150=7/50
intercept: 40=(7/50)(300)+b; 40=42+b; b=-2
EQUATION: tail=(7/50)(length)-2
b. Use this linear equation to estimate the tail length of a snake with a total length of 200 mm.
t=(7/50)200-2
t=26 mm
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c. Use this linear equation to estimate the tail length of a snake with a total length of 350 mm. 
t=(7/50)(350)-2
t=47 mm
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Cheers,
Stan H.