Question 106987
I get the same answer
What's the rate of using fuel when idling?
(1 tank) / 38 hours
Whats the rate of using fuel at 60 mph?
(3.5 tanks) / 38 hours
Now to use up 1 tankful,
(idle rate*idle time) + (run rate*run time) = 1 tank
{1 tank/38 hours)*10 hours + (3.5 tanks/38 hours)*(run time) = 1 tank
{{{10/38 + (3.5/38)*t[r] = 1}}}
{{{10 + 3.5t[r] = 38}}}
{{{3.5t[r] = 28}}}
{{{t[r] = 28/3.5}}}
{{{t[r] = 8 hours}}} answer