## alfers101 3 years ago on a trip a family averaged 65km/hr for the first hour 50km/hr for the second hour and 58 km/hr for the third hour. what was their average speed?

1. mathslover

a physics question @alfers101 please post this in physics section

2. mathslover

3. mathslover

given : 1) at t =1 hr. , average speed = 65 kmph 2) at t = 2hr. , average speed = 58 kmph so we know that: $\large{\frac{\textbf{total distance travelled}}{\textbf{total time taken}}=\textbf{average speed}}$

4. mathslover

Oh sorry wait

5. lgbasallote

also remember that $\huge \frac{\text{speed}_1 + \text{speed}_2}{2} \ne \text{average speed}$ just saying

6. alfers101

ok

7. alfers101

thanks

8. mathslover

thanks? u got it soo soon @alfers101 ?

9. alfers101

no i still dont :( but i have the idea but i dont know how to answer this

10. mathslover

oh k so what is the idea?

11. mathslover

do you have the answer alfers101?

12. phi

FIrst, find how far they drove. Use speed*time= distance they drove 65km/hr for the first hour: distance= 65*1 do the same thing for the 2nd hour (using the new speed), and the 3rd hour add up the distances now use speed*time= distance speed= distance/time distance will be the total distance time will be the total time ( 3 hours)