Today’s problem — free all day, every step. Every day has one.
Cycling race — Mei and Lin
Mei and Lin took part in a cycling race. Mei cycled at a speed of 20 km/h. Both of them did not change their speed throughout the race. When Lin covered of the distance, Mei was 3.5 km in front of her. Mei reached the finishing line at 10.45 a.m. What time did Lin reach the finishing line?
See all 6 steps
MathBrush is being tested with a few parent groups, and every solution on the site is open to them — one household, all children. If you were given a code, it goes in once and this device remembers it.
I have a code → See a free one like it
65 worked examples are free without a code, two from every pattern. No account, either way.
The pattern behind it: Same time, same distance
Two travellers spend the same time, or cover the same distance.
In this one. At constant speeds the gap grows in proportion to how far they have gone, so doubling Lin's distance doubles Mei's lead — and a lead in km becomes a lead in time by dividing by the speed.
How to spot it
Two travellers set off together or one chases another, with constant speeds and a question about who is ahead, when they meet, or how far apart they are.
Common mistake
Children divide the whole distance by the difference in speed instead of dividing the gap between the travellers, or compare distances covered over different lengths of time.
Try one like it
Standard Aladdin and Jasmine — the magic carpet race Aladdin and Jasmine were having a race on their magic flying carpets. They left the same starting point for the market at 13 00. B…The 33 problem patterns
All 33 patterns, one to a page — the 19 behind Primary 5 and 6 word problems, and the skills the younger years are built on. The bar model, how to spot it in the question, and the mistake children make. A booklet you can print. Free.
A PDF, and a note when new solutions go up.