Question 1084090
Rate x Time = Distance,
For the first 30 km,
{{{30*t=30}}}
{{{t=1}}}{{{hr}}}
So then to get the average velocity,
Using the distance formula,
1.{{{30+V[2]*t[2]=100}}}
and using the average velocity,
2.{{{(30*1+V[2]*t[2])/(1+t[2])=40}}}
So then,
{{{30+V[2]*t[2]=40(1+t[2])}}}
Substituting into 1,
{{{40(1+t[2])=100}}}
{{{1+t[2]=5/2}}}
{{{t[2]=3/2}}}{{{hr}}}
So then from 1,
{{{30+V[2](3/2)=100}}}
{{{V[2](3/2)=70}}}
{{{V[2]=140/3}}}{{{km/hr}}}