Question

a crew rowed 20 miles downstream, with the current, in 2 hours. the return trip upstream, against the current, same distance, took 5 hours. find the crews rowing rate and rate of the current

Answer 1

i know i do rate * time =distance

Answer 2

ahh downstream-upstream...

downstream speed = speed of boat (still) + speed of current
upstream speed = speed of boat (still) - speed of current

let c = current; b = speed of boat (still)

we need to find both huh...okay...

it says downstream..they went 20 miles in 2 hours so...that's 10 mile/hr

upstream speed...20 miles in 5 hrs so 4 mile/hr

are you following? :)

Answer 3

so.... R*2 = 20 R=10..... and then R=4 for the other, but idk exactly what i just solved as far as the rates?

Answer 4

ya i am so far
i feel like this is like the one the other day, so easy its hard :(

Answer 5

hahaha no....look at the equation i wrote above..

downstream speed = speed of boat + current
upstream speed = speed of boat - current

we already have downstream and upstream speeds..and if you look close if you do a system there..current will calncel out and leave you with the speed of boat only right?

Answer 6

current will cancel out*

Answer 7

so...do you have an idea of the next step now? :D

Answer 8

6?

Answer 9

6? do you mean that's your speed of boat? i dont think so haha...why dont you post your solution here so we can see where you went wrong...

Answer 10

so if the currents cancel out wouldnt that be 10-6

Answer 11

10 being rate w current, and 4 against?

Answer 12

no no no....we do a systems..okay i will do the next step....

i said we let b = boat; c = current so...

10 = b + c <---downstream speed
4 = b - c <----upstream speed

do you see it now?

Answer 13

how do i figure out the current speed then?

Answer 14

33 ?s and i have probelm with one haha!! wth!

Answer 15

wait so b=4 and 10? do i add them or subtract?
i would assume subtract....which would be 6!

Answer 16

ok ok... boat is 7 and current is 3???!!!

Answer 17

no no no... 4 is the upstream speed..10 is the downstream speed..you do not have a b..you're looking for it remember? wait...do you know how to use systems of linear equations?

Answer 18

not exactly i guess?

Answer 19

i feel like the boat is 7 and current is 3

Answer 20

actually i only have 3 minutes to answer this one ? so im going to just have to accept a missed one lol
BUUTTTT thanks for all your help with this one

Answer 21

hmmm how did you do it?

Answer 22

actually...you're right :P

Answer 23

i used substitution method actually... is that right then

Answer 24

ok then boat is the row speed correct?

Answer 25

yup

Answer 26

THANK U SOOOO MUCH!!!

Answer 27

<tips hat>