SAT math - Average speed

Test Preparation
1

<p>Hi guys,
I can't really do this kind of question forexample when you have someone travelling from their house to a place at certain speed , same route - same distance. Instead s/he returns home with different average speed. Now the question asks for the average speed for the whole journey.. Please help also sometimes they don't tell you everything because we need to know the distance, speed, time right? sometimes they give me only 1 at most 2 . Please help ,sorry if I asked too much.</p>

<p>Thank you!</p>

2

<p>(rate1)(rate2)(2)/(rate1+rate2)</p>

3

<p>Thank you, but what if they ask for time or distance without knowing the other info?</p>

4

<p>Average rate = (total distance)/(total time). Usually you should be given enough information to determine the unknowns.</p>

5

<p>total distance/total time</p>