Answer
\approx 2305 miles
Work Step by Step
This problem can be solved using the formula given in the problem: Distance = \frac{7-x}{0.639x + 1.75}. Since the question asks about the distance of a river that has an altitude of 1200 ft, convert the 1200 ft into thousands of feet for the variable x by dividing 1200 by 1000. Therefore, x = 1.2.
Now, substitute 1.2 for x into the formula, which gives the expression:
\frac{7 - 1.2}{0.639(1.2) + 1.75}
Next, simplify the expression, and get the distance.
\frac{7 - 1.2}{0.639(1.2) + 1.75} = \frac{5.8}{0.7668 + 1.75} = \frac{5.8}{2.5168} \approx 2.3045
Then, multiply 2.3045 by 1000, which gives 2304.5 miles. Since the question asks about the nearest mile, round 2304.5 into 2305 miles.
As a result, the distance from the origin of the Nile when the river has an altitude of 1200 ft is around 2305 miles.
