A boat has 2 motors, one large and one small. If only the large motor is running, a tank of fuel lasts 2 h. If only the small motor is running, the tank of fuel lasts 4 h. How long will the fuel last if both motors are running?

Question

raden · Answer

short cut !
t=(2*4)/(2+4)=....?
t=time

anonymous · Answer

thank you ! is there any other way of solving this?

raden · Answer

welcome,,
t1+t2=1/2 + 1/4 = 2/4+1/4 = 3/4 = 1/(4/3)
so, both motor are running 4/3 hours = 4/3 * 60 minutes = 80 minutes = 1 hour + 20 m