Question

An Uber fare in San Diego is $3.50 for the first ½ mile and additional mileage charged at a rate of $0.30 for each additional 0.1 mile. You plan to give the driver a $2 tip. How many miles can you ride for $15? Please show or explain your calculations.

Answer 1

3.6 miles

Explanation:

For a trip of x miles, there are x-0.5 miles of it that are "additional", which makes (x-0.5)/0.1 additional tenths.

Then the charges (in dollars) are ...

... 3.50 + 0.30(x -0.5)/0.1

Adding a tip of $2 and requiring the total be less than $15 gives ...

... 3.50 + 0.30(x -0.5) + 2.00 ≤ 15.00

... 5.50 + 3(x - 0.5) ≤ 15.00 . . . . simplify a bit

... 4.00 +3x ≤ 15.00 . . . . . . . . . . simplify more

... 3x ≤ 11.00 . . . . . . subtract 4.00

... x ≤ 3.667 . . . . . . divide by 3

Miles are measured in tenths. We cannot go 3.7 miles on $15, but we can go 3.6 miles.