Can you check my answers please?

It looks ok but the last question I think is wrong since you just added one side of each length instead of 2. Think of it as a rectangle and you have just added 2 lines of that rectangle instead of all the lines.

Also, it would be easier to divide the 1000m by what you get after adding the 4 sides as you would not have to guess what times into it to get just over 1000.

Calculation in 2 is wrong - answers in 3 are also incorrect.

2) 154 x 40 is over 6000

3) It asks for the error not the value and upper bound is wrong

2) 154 x 40 is over 6000

3) It asks for the error not the value and upper bound is wrong

6160 ok I see where I made my mistake it was with 50 x 40.

Right so how do you answer error?

It means the greatest possible error away from the actual measurement. So the lower bound is 505kg and the upper bound is 515kg. The horse could weigh 505kg so the maximum error would be 10 kg I think.

But if I say 515kg then that would mean it would actually be for 520kg not 510kg since 515kg would round up to 520kg if given to the nearest 10kg.

No that’s not how bounds work unfortunately.
They are usually written as:
p<_ x <q where p is the lower bound and q is the upper bound (excuse the keyboard symbols). So the upper bound is 515kg

Oh I see so it is the limit but isn't what is included.

So only 5.15 and 5.24 is the actual values but the limiters are 5.14 and 5.25

No it’s 505kg as the lower bound and 515kg as the upper bound giving the maximum error as 10kg. I’m not 100% sure though but I think I’m right

The max error is 5 not 10