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

The expression relating the distance and the time is:
velocity = distance / time

We are given the velocity as 12 km/h

Part a:
for t = 3.5 hours
velocity = distance / time
distance = velocity x time
distance = 12 x 3.5 = 42 km

Part b:
for s = 30 km
velocity = distance / time
time = distance / velocity
time = 30 / 12 = 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

$V=12\frac{Km}{h}$

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

$2.5\ h$