PROBLEM
John drove for 2 hours at a speed of 70 km/h and another 3 hours at a speed of 60 km. What is the average speed for the whole journey?

STEP 1 Read the problem and extract important information SHOW ME

70 km/h for 2 hours ; 60 km/h for 3 hours

STEP 2 Read the question again; extract important information and write a formula that might help in answering the question. SHOW ME

average speed ; whole journey

average speed = (total distance / total time)

STEP 3 Write equations and solve the problem. SHOW ME

total distance = 70 km/h * 2 h + 60 km/h * 3 h
= 140 + 180 = 320 km


SHOW ME

total time = 2 hours + 3 hours = 5 hours


SHOW ME

average speed = (total distance / total time)
= 320 km / (2 h + 3 h) = 64 km / h