2 original ESAT Maths 1 units questions in the real exam style, each with a step-by-step worked solution and an explanation of why the tempting wrong answers are wrong. Try each one before opening the solution.
Methods on this page:Average speed = total distance ÷ total time
Question 1ESAT Maths 1Standard
A training session repeats this 3-part routine several times:
Walk 400m at an average speed of 24km h−1 Jog 100m at an average speed of 4km h−1 Run 100m at an average speed of 12km h−1
What is the average speed for the whole session, in km h−1?
A10
B11
C12
D13
E340
F14
G15
H356
Show the answer and worked solution
Answer: C · Method: Average speed = total distance ÷ total time
Total distance: 600m=53km.
Total time: 240.4+40.1+120.1=201 hours.
Average speed =53÷201=12km h−1.
Why the tempting wrong answers are wrong
E: You can't average the speeds: each part takes a different amount of time.
H: Weighting the speeds by distance still isn't right. Find the total time.