Read a rate as 'for each'

1 · Learn

A rate connects quantities, such as £3 for each ticket or 60 words for each minute in a made-up steady-rate example. State the assumption if the rate is treated as constant.

Time conversions use 60 minutes per hour and 60 seconds per minute. Three hours and twenty minutes is 200 minutes, not 320. Use all four operations when a context needs them.

Scaling can use a fraction. A full-size model strip is 18 cm long. At half-size, multiply by one half, or divide by two: 9 cm. At one-and-a-half size, add the full 18 cm and half of it: 27 cm. The same scale must be used for every length in a scale drawing.

2 · Worked example

At a constant model rate of 60 words per minute, five minutes gives 300 words. Real reading speed may vary, so the model is an assumption.

3 · Your turn

A journey lasts 2 hours 35 minutes and a break lasts 25 minutes. Find the combined duration in minutes and hours.

4 · Apply your learning

Solve a safe timetable or money problem and explain every conversion and any constant-rate assumption.