<PRE><B>Question 525907</B>
If you bike for 2 hours at 30km/h and for 2 hours at 20 km/h, what is your average speed for the whole trip?
:
Find the total distance of the trip: (2*30) + (2*20) = 100 km
:
let a = the average speed for the whole trip
:
Write time time equation, time = dist/speed
{{{60/30}}} + {{{40/20}}} = {{{100/a}}}
2 + 2 = {{{100/a}}}
4 = {{{100/a}}}
4a = 100
a = 25 km/hr</PRE>