Maths 11+ question… am I missing something?

[Fat hippo]

Attached question along with suggested workings.

I don’t think it can be solved in the way described as the width of the rectangle is not given and not sure how it can be assumed to be 1 (or am I being thick here)?

Also not sure how they derived width + length being 18 and likewise where does the 5/9 come from?

[JimbobVFR]

The outside square has to be 18x18 because it's half the perimeter of one of the rectangles (made up of 1 short length and one long length)

The perimeter is given as 36 so it's half of it.

This gives you the total area. (18x18)

The centre square is 5 times the area of the small rectangle meaning the total area is 9 times the area of the rectangle therefore the centre square is 5/9 of the total area.

Once you have the area of the internal square then the square root will give you the length of the smaller squares sides.

Edited by JimbobVFR on Sunday 6th November 23:55

Edited by JimbobVFR on Sunday 6th November 23:56

[Fat hippo]

Thanks. I can see im being thick on the first part. Get that now.
Just not clear about the 9

[JimbobVFR]

Fat hippo said:

Just not clear about the 9

The central square is 5 times the area of one of the small rectangles.

There's 4 rectangles plus the area of the square equivalent to 5 of the rectangles giving the 9.

[Fat hippo]

Thanks for that. Clear now.
I think I am thick. Should have got that quicker

[Tango13]

The centimeter is not a recognised unit of measurement in the engineering industry so if I was given that drawing I'd send it back and tell who ever was responsible to do it correctly.

[drmike37]

11 plus has got harder. I couldn't do that and I did further maths.... (a long time ago)

[gazza285]

Tango13 said:

The centimeter is not a recognised unit of measurement in the engineering industry so if I was given that drawing I'd send it back and tell who ever was responsible to do it correctly.

And learn to spell?

[mikey_b]

drmike37 said:

11 plus has got harder. I couldn't do that and I did further maths.... (a long time ago)

I think it varies depending where you are. My daughter took the 11+ in Kent a couple of months ago, so we are very familiar with it. All the questions in the Kent Test are multiple choice and are designed to be done at speed mostly in your head (you get, very roughly, 60 seconds per question although it varies by paper and section) which this question clearly isn’t.

Is that question from a genuine UK 11+ paper?