Question

HELP PLEASE!!!
In driving the usual route to school a student computes his average speed to be 30km/h. In a hurry to get home that afternoon he wants to average 60km/h for the round trip. What would be his average speed for the return trip over the same route have to be in order to do this?????
Support mathematically??

Answer 1

what grade are you in?

Answer 2

Y?

Answer 3

Y??

Answer 4

so i know how to help you

Answer 5

11th

Answer 6

45 i think?!

Answer 7

The mathematical formula:
The average speed for roundtrip=(The average speed to get to school + the average speed to get to your home)/2
keep in mind that the formula for the mean (average) is the sum of all of the numbers in a list divided by the number of items in that list.

Answer 8

see i was right :D

Answer 9

lets treat the average speed to get home as our variable x:\[(30+x)\div2=60\]

Answer 10

can you work the problem out from here on?

Answer 11

Ok but our book says its impossible but I have to prove that and that's y I'm confused I had your answer originally but the I was told it would have to be infinity for it to work but I need to prove this mathematically

Answer 12

who are you talking to Lulu212?:D

Answer 13

Either one of u

Answer 14

By the way Lorii95 is wrong, if you work out the problem you can see that x = 90:
\[(30+x)=60*2\] \[x=120-30\] \[x = 90\]

Answer 15

Ok thanks