Problem 3 - The Wall
Problem 3 is all about working with decimals and 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.
So here's the challenge:
A street artist likes to get people thinking, so his latest work is a number puzzle within a pyramid.
In this pyramid, four of the bricks are marked with numbers and a fifth contains a question mark.
The numbers on a particular brick can be found by adding the numbers on the two bricks underneath it.
So, the sum of 0.8 and 陆 should be written on the pink brick.
What number should be on the brick marked with a question mark?
Need a hint?
- It's tricky to add decimals and fractions - can you make this easier?
- Could you try drawing it out and adding the answers you know help?
- Can you work your way up the pyramid and then back down?
Solution
Worked out the answer? Here's how you can do it.
Step 1
This problem involves decimals and fractions - it's probably easier if we convert the fractions to decimals first.
So let's change 陆 to 0.5
Step 2
Then 0.5 + 0.8 will give us 1.3 for the pink brick.
To find out the value of the brick with the question mark, we鈥檙e going to have to work our way round to it.
Step 3
We can change 3/20 to 0.15 and add that with 0.8 to get 0.95.
Step 4
If we then do 0.95 + 1.3, we will get 2.25
Step 5
Now that we have one part of the value of the top brick, we can subtract this to find the value of the brick next to it.
So, 3.4 - 2.25 means the other brick must be 1.15
Step 6
Next 1.15 subtract 0.95 to gives us 0.2
Step 7
0.2 subtract 0.15 gives us 0.05.
So the value of the brick with the question mark is 0.05
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