In the 2016 Olympics, Joseph Schooling won the first Olympics gold medal for Singapore in the 100 m butterfly with a timing of 50.39 seconds. Consider the accuracy of the instruments used to measure the timings of the swimmers.
Is ‘50.39’ an approximation or an exact value?
It is an approximation. No measuring instrument is perfectly precise — chip timing systems typically have an accuracy of about 0.001 s. The "true" time is somewhere in a small range around 50.39 s (e.g. 50.385 s ≤ true time < 50.395 s). When we round it to 2 d.p., we get 50.39.
Why do you think we often use approximations and estimations in our daily lives?
📚 本章学习目标 · Learning objectives
Approximate values by rounding off numbers to specified
place values (e.g., nearest 10, 100, 1000)
decimal places (1 d.p., 2 d.p., …)
significant figures (1 s.f., 2 s.f., …)
Approximate values by using estimation
Apply estimation in real-life situations (shopping, measurements, computation checks)