Question

There are three tunnels A, B, and C, and the length of the tunnels are in the proportion of 2:4:1, respectively. If a train takes 16 seconds to travel through tunnel A and 30 seconds to travel through tunnel B, how long does it take to travel through tunnel C?

Answer 1

any ideas guys?

Answer 2

its a ratio question.

Answer 3

u know how to do it?

Answer 4

think of the ratio as lengths

Answer 5

2:4:1

Answer 6

length A=? B=? C=?...

Answer 7

like A =2, B=4, C=1?

Answer 8

right

Answer 9

but I don't get the time part?

Answer 10

with the seconds

Answer 11

v=d/t so if velocity is the same lets say v=1. solve for d

Answer 12

because we want to find the distance of tunnel c

Answer 13

how do u solve for d? what's the value for t?

Answer 14

i got of track a bit we want to find the time to travel c and if v*d=t and v=1 t=?

Answer 15

so if you know the ratio of the distances you also know the ratio of the ....?

Answer 16

the time?

Answer 17

right.

Answer 18

replace A time= B time = C time = and what the ratio between them.

Answer 19

wait what?

Answer 20

how does that work though? the time of A: B is 16:30, which is not 2:4

Answer 21

or double the time i assume it is using significant figures. so ~2x16=30 or its a book typo because a train that slows down and speeds up would make this problem very hard.

Answer 22

so the answer should be what?

Answer 23

are you sure its 16 not 15?

Answer 24

or 32 not 30.?

Answer 25

it's on my paper

Answer 26

anyway, the answer would be either 15 or 16 right?

Answer 27

1/4 of 32 =

Answer 28

ok sorry we assumed that v = 1

Answer 29

so we have to solve for v

Answer 30

not equal to 1

Answer 31

oops I meant 7.5 or 8 right?

Answer 32

right but i think 30 is wrong and should be 32 so its 8

Answer 33

k

Answer 34

thanks

Answer 35

can u help me with some more?

Answer 36

sure

Answer 37

Dad is now 43 years old and son is now 13. How many years will pass so that dad's age is twice his son's age?

Answer 38

I know it's 17 but how do I do it the algebraic way?

Answer 39

so

Answer 40

we have two variables D=dad's age and S= sons age

Answer 41

and a ratio

Answer 42

D= 2S right?

Answer 43

does this make sense

Answer 44

yea

Answer 45

then what?

Answer 46

there is one unknown n = number of years that between know and when the ratio holds.

Answer 47

and they each age by n

Answer 48

(43+n)=2(13+n) solve for n

Answer 49

(D+nyears)/(S +nyears)=2

Answer 50

ur so smart :)

Answer 51

haha cheers. I got to go have a good day.

Answer 52

2 more questions, is that ok?

Answer 53

it will be quick

Answer 54

I cant man sorry. good luck.