a car travels 200km with speed of 100km/hr for 100km it travels with the speed of 40km/hr. calculate the average speed of the car
Answers
To solve this problem, we’ll utilize the “time-speed-distance” relationship which is expressed by the formula d = rt, i.e., distance is equal to speed multiplied by time.
We’re given that d = 200 km and t = 2 hours and 24 minutes = (2 and 24/60) hours = 2⅖ hours = 2.4 hours. Now, substitute the given value for d and the given value for t into the time-speed-distance formula and then solve for speed r as follows:
d = rt
200 km = r(2.4 hours)
r(2.4 hours) = 200 km (Equality is symmetric, i.e. if a = b, then b = a.)
Let’s get rid of the decimal, i.e., 2.4, by multiplying both sides of the equation by 10:
r(2.4 hours)(10) = (200 km)(10)
r(24 hours) = 2000 km
Now, divide both sides of the equation by “24 hours” to isolate the unknown speed r by itself on the left side:
[r(24 hours)]/24 hours = 2000 km/24 hours
r(24 hours/24 hours) = 2000 km/24 hours
r(1) = 2000 km/24 hours
On the right side of the equation, divide both the numerator and the denominator by 24 as follows:
r = (2000/24)km/(24/24) hour
r = (2000/24) km/1 hour
r = (2000/24) km/hr.
r = 83⅓ km/hr. is the average speed that the car is traveling.
