Four cyclists rode part of a 45 km charity route. Farah rode 715 of the route, Gavin rode 35, Hui Min rode 59 and Jun rode 23.
- Find the lowest common denominator of 15, 5, 9 and 3. [1 mark]
- Write each of the four fractions with this common denominator. [2 marks]
- Arrange the four names from the one who rode the least to the one who rode the most. [1 mark]
Need a hint?
Find a number that 15, 5, 9 and 3 all divide into, then multiply the top and bottom of each fraction to reach it.
Worked answer
- (a) 15, 5, 9 and 3 all divide into 45, and no smaller number works, so the LCD is 45.
- (b) 715 = 2145 and 59 = 2545.
- (b) 35 = 2745 and 23 = 3045.
- (c) Compare numerators over 45: 21 < 25 < 27 < 30, so Farah, Hui Min, Gavin, Jun.
Answer: Farah, Hui Min, Gavin, Jun
The mistake this question tests
Habit
Factors and multiples (HCF, LCM)
Pupils compare the denominators or numerators directly without making the denominators equal, so they may rank 23 as the smallest because 3 is the smallest denominator.
How to fix it at home →More PSLE fractions questions
Short answer · 2m
Four pupils each painted a fraction of a fence in the school garden
See the answer →Structured · 3mThree pupils each filled part of a bucket with sand
See the answer →MCQ · 1mFour gardeners each watered a fraction of their flower bed before lunch
See the answer →Structured · 5mFour pupils each read a fraction of a storybook during a reading challenge
See the answer →MCQ · 1mWhich of these is equal to 3/4 ÷ 3?
See the answer →Short answer · 3mMrs Tan baked some cookies
See the answer →Practise PSLE fractions until the mistakes stop.
Three PSLE questions, free, no sign-up. You’ll see exactly where the marks went. Then 7 days of everything for S$4.99.