Quantitive Literacy-> I need help with this math problem.

Question

You're going on a 1211-mile trip, and your car gets about 29 miles per gallon. Gas prices along your route average $1.99. Estimate the cost of gasoline for this trip by rounding the distance to 1200 miles, the mileage to 30 miles per gallon, and the cost of gas to $2.00 per gallon. Calculate the answer without using estimation and compare the two results. (Round your answers to the nearest cent.) It's asking for the estimated and exact price.

Answer 1

Belle,

 

Lets use the estimation first

 

Distance = 1200 miles, mileage = 30 miles per gallon

So fuel used = 1200/30 = 40 gallons

Cost is $2/gallon so total estimated cost = 2*40 = $80

 

Now using the real numbers 

Fuel used = 1211/29 gallons

Actual cost = 1.99*1211/29 = $83.10

 

So actual cost is $3.10 higher than the estimated cost