Using Ratios To Estimate Sizes

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Lately, in math class we’ve been studying on ratios. Because we got some knowledge about ratios after doing one assessment, we started to use our understanding on another (pre)assessment.

So basically we just; we Partner up (I’m with Aisling). Then choose any 2 different sized objects, measure the size of the smaller sized object and estimate the length of the other object we chose using the knowledge of ratios. We decided that we should estimate the length of the macbook air we use at school with a 3cm(length) eraser.


Since taking a photo and editing it to make it easier and accurate to estimate the length of the bigger object we made the picture on the very top using pages. By looking at it we estimated that the the length of the eraser compared to the macbook air would be about 1:9.

That means that to figure out the size of the macbook air we need to multiply 4 and 9.

4 × 9 = 36

Estimation of macbook air’s length: 36cm

After we estimated the length(36cm), we measured the macbook air to check the real length of it. As a result, we figured out that the macbook air’s length is about 30cm long. Our estimation wasn’t right because the result was 6cm over but I think it was pretty close.

I think if you want to estimate the length of something and don’t really need detail for the result I think this method is a good one to use.