Question

Sound travels about 343 meters per second. The function d(t)=343t gives the distance d(t) in meters that sound travels in t seconds. How far does sound travel in 8 seconds?

Answer 1

what do you think?

Answer 2

A. 343 meters
B. 686 meters
C. 2744 meters
D. 3430 meters

I believe it is either A or C, but I'm not sure.

Answer 3

Why A? why C?

Answer 4

in d(t)=343t I did d(8)=343(8) and got 343, but 343 times 8 equals 2477 and 343 meters per second for 8 seconds would be 2477 meters.

Answer 5

343(8) is the same thing as 343 times 8... it's just another way of writing it.

Answer 6

Yes, but do I multiply d by 8 or not?

Answer 7

Because if I do d(8) then my answer will be 343, but if I don't then it will be 2477.

Answer 8

hmm I see.
d(t) might look like d multiplied by t but it isn't. It means that for an input t you get an output d. To show that the variable d is dependent on t you write d(t)

Answer 9

so d(8) is not d times 8, it is actually d evaluated when t=8

Answer 10

Oh, ok. Thank you. So then the answer should be C. 2477 meters ?

Answer 11

Yes. Note that the variable d is chosen because d is short for distance. d(t) is another way of writing d, and this way just shows that d takes t as an input

Answer 12

(and d is the output)

Answer 13

Yes, thank you so much for all of your help! :)

Answer 14

No problem! :)