1. The formula expressing the dependence of the variable s on t is: s = 60 - 12t
2. the distance travelled at time t = 3.5 h is 18 Km
Speed is the distance travelled per unit. Mathematically, it can be expressed as:
Speed = distance / time
From the question given, bicyclist traveled with a speed of 12 km/h from a camping ground to a station, located 60 km.
Thus, we shall determine the distance travel in time t as follow
Speed = distance / time
12 = distance / t
Cross multiply
Distance = 12 × t
Distance in time t = 12t
But the total distance travelled is 60 Km. Thus, the remaining distance (s) from the bicyclist to the station at time (t) will be given as:
s = 60 - 12t
Thus, the formula expressing the dependence of the variable s on t is: s = 60 - 12t
The distance at t = 3.5 hours can be obtained as illustrated below:
s = 60 - 12t
s = 60 - (12 × 3.5)
s = 60 - 42
s = 18 Km
Thus, the distance travelled at t = 3.5 hours is 18 km
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