Question

A bicyclist traveled with a speed of 12 km/h from a camping ground to a station, located 60 km away. Write a formula expressing the dependence of the variable s on t, where s is the distance between the bicyclist and the station in km, t - the duration (time) of his travel in hours. Using the formula, find s for t=3.5 AND t for s=30 (AND = separate)

Answer 1

Part A) 18 km Part B) 2.5 hours

Explanation:

Part A:

Formula: s = 60 - 12t

Substitute numbers:

s = 60 - 12(3.5) = 60 - 42 = 18 km

Part B:

Formula: s = 60 - 12t

Substitute numbers:

30 = 60 - 12t

30 - 60 = -12t

-30 = -12t

t = 2.5 hours

Answer 2

Let

s-------> is the distance in Kilometer

V-----> the speed of the bicyclist in Km/h

t------> is the time in hours

we know that

`V=s/t`

in this problem we have

`V=12(Km)/(h)`

Part a) Find s for
`t=3.5\ h`

we know that

`V=s/t`

solve for s

`s=Vt`

substitute the values

`s=12*3.5=42\ Km`

therefore

the answer Part a) is

`42\ Km`

Part b) Find t for
`s=30\ Km`

we know that

`V=s/t`

solve for t

`t=s/V`

substitute the values

`t=30/12=2.5\ h`

therefore

the answer Part b) is

`2.5\ h`