Question

A motorboat travels 522 in 6 hours going upstream and 882 in 7 hours going downstream. What is the rate of the boat in still water and what is the rate of the current?

Answer 1

you're missing some units of measurement in 522 and 882

Answer 2

miles

Answer 3

sorry

Answer 4

hmm ok...you know that speed = distance/time right?

Answer 5

i did not

Answer 6

well now you do

Answer 7

one more thing...

downstream speed = speed of boat + speed of current

upstream speed = speed of boat - speed of current

Answer 8

got that?

Answer 9

uhh maybe ill try plug in the numbers just check my work

Answer 10

okay then

Answer 11

speed of current?

Answer 12

what do you mean?

Answer 13

i have know idea how to get that

Answer 14

okay then..shall i step in?

Answer 15

i think that make me grasp this problem

Answer 16

would*

Answer 17

okay then...first let's use letters to make these shorter

let speed of boat = b
speed of current = c

therefore

downstream speed = b + c

upstream speed = b - c

okay?

Answer 18

ok

Answer 19

upstream speed 87

Answer 20

btw...can you recheck your question? is it really like that?

Answer 21

just asking

Answer 22

yes it wants me to find the rate boats in still water and rate of the current

Answer 23

ok good...so you're right upstream speed is 87

what is downstream speed then?

Answer 24

126

Answer 25

good..let's plug those in

126 = b + c

87 = b - c

are you seeing the next step now? :)

Answer 26

sadly no

Answer 27

you use systems of equations ;) see how if you add the equations c will cancel out?

Answer 28

so 126c=b

Answer 29

hmm that's not what i meant hehe

Answer 30

im sorry

Answer 31

but we can use substitution..but it would be

b = 126 - c

got it?

Answer 32

ight now what

Answer 33

now substitute that into the b of

87 = b - c

it will ebcome

87 = 126 - c - c

got it?

Answer 34

c=39

Answer 35

not exactly...

87 - 126 = -c - c

-39 = -2c

Answer 36

you have to find c

Answer 37

c=19.5

Answer 38

yup better

Answer 39

so?

Answer 40

now that is the speed of current

with this you can also find the speed of the boat

Answer 41

how bro? if havent caught im kinda bad at math

Answer 42

nahh you caught up fast

remember how

126 = b + c

Answer 43

so the rate of the current is 19.5

Answer 44

yup

Answer 45

b=106.5

Answer 46

?

Answer 47

yup

Answer 48

you can check by seeing if

87 = 106.5 - 19.5

Answer 49

so the rate of th boat in still water is b?