Question

the average speed of 20km/hr,16km/hr,12km/hr?

Answer 1

20*16*12/20+16+12=80

Answer 2

the average is 16

Answer 3

how?

Answer 4

20 + 16 + 12 = 48/3 = 16

Answer 5

well i got 3 because there are 3 numbers

Answer 6

nope

Answer 7

I think you need to do below :

average speed = \[\large \dfrac{3(20*16*12)}{12*16 + 16*12 + 12*20}\]

Answer 8

http://www.wolframalpha.com/input/?i=3*%2820*16*12%29%2F%2820*16%2B16*12%2B12*20%29

Answer 9

say you have travelled first 1/3rd of distance at 20km/hr
next 1/3rd of distance at 16km/hr
and the last 1/3rd of distance at 12 km/hr

Answer 10

then, total distance = d/3 + d/3 + d/3 = d

Answer 11

time taken while covering first 1/3rd of distance = \(\large \dfrac{d/3}{20}\)

time taken while covering second1/3rd of distance = \(\large \dfrac{d/3}{16}\)

time taken while covering last /3rd of distance = \(\large \dfrac{d/3}{12}\)

Answer 12

yes exACTLY @ganeshie8

Answer 13

so total time taken for covering a distance of "d" =

\(\large \dfrac{d/3}{20} + \dfrac{d/3}{16} + \dfrac{d/3}{12} \)

Answer 14

average speed = (total distance)/(total time)

= \(\large \dfrac{d}{\dfrac{d/3}{20} + \dfrac{d/3}{16} + \dfrac{d/3}{12}} \)

Answer 15

= \(\large \dfrac{1}{\dfrac{1/3}{20} + \dfrac{1/3}{16} + \dfrac{1/3}{12}} \)

Answer 16

= \(\large \dfrac{3}{\dfrac{1}{20} + \dfrac{1}{16} + \dfrac{1}{12}} \)

Answer 17

you can simplify

Answer 18

15.31

Answer 19

rounds to 15.32 :)
http://www.wolframalpha.com/input/?i=3*%2820*16*12%29%2F%2820*16%2B16*12%2B12*20%29