Challenge 5 - Painting the flats
Challenge 5 is all about fractions.
Maths teacher Chris Smith and pupils from Grange Academy are here to explain.
The Maths Week Scotland Daily Challenges have been set by the Scottish Mathematical Council.
Mr Smith: This problem is all about fractions.
The Hillside Estate on the edge of the city consists of eight tower blocks. Each tower block has nine floors and each floor has ten flats.
The council painters have just arrived and they’re wondering just how many flats need to be painted this year.
Two in five of the flats are privately owned, so they will not be painted by the council.
Of the rest, one in four flats will be left to next year.
How many flats are to be painted by the council this year?
Explain your answer.
Pupil: You could draw this out or use blocks to help you visualise this problem.
Pupil: It might help to work through this in separate stages.
Pupil: Think about how you work with fractions.
Pupil: Good luck!
So here's the challenge:
This problem is all about fractions.
The Hillside Estate on the edge of the city consists of eight tower blocks.
Each tower block has nine floors and each floor has ten flats.
The council painters have just arrived and they’re wondering just how many flats need to be painted this year.
Two in five of the flats are privately owned, so they will not be painted by the council.
Of the rest, one in four flats will be left to next year.
How many flats are to be painted by the council this year?

Need a hint?
- You could draw this out or use blocks to help you visualise this problem.
- It might help to work through this in separate stages.
- Think about how you work with fractions.
Solution
Worked out the answer? Here's how you can do it.
Did you work out the number of flats to be painted?
Let’s look at how we got our answer.
We can work this out in stages, so first let's work out the total number of flats.
There are eight blocks of flats, with nine floors, and ten flats on each floor.
So that's 8 x 9 x 10, which is 720.
Two in five flats are privately owned, so three in five, or 3/5 need to be painted.
3/5 x 720 = 432.
One in four flats are being left until next year.
That means three out of four, or three quarters of the flats are to be painted, ¾ x 432 = 324
Great job if you had this one covered.

Step 1
We can work this out in stages, so first let's work out the total number of flats.
There are eight blocks of flats, with nine floors, and ten flats on each floor.
So that's 8 x 9 x 10 = 720


Step 2
Two in five flats are privately owned, so three in five, or 3/5 need to be painted.
3/5 x 720 = 432


Step 3
One in four flats are being left until next year.
That means three out of four, or three quarters of the flats are to be painted,
¾ x 432 = 324
324 flats are to be painted this year.

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