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Original poster

Maths teacher or maths whizz? This way please!

38 replies

Orangeplastic · 24/10/2017 10:16

A recent question in a Maths test.....

Joe weighed 45kg to the nearest kilo. What is the highest and lowest possible value of his weight?

Ds got this question wrong - he thought he was right, he questioned the teacher but she insisted he was wrong and we are not sure why.

OP posts:
AtiaoftheJulii · 24/10/2017 11:47

Well, Joe could weigh more than 45.49 kg - 45.494378655 kg for example, so as a convention we say 45.5kg. I'd assume that was covered in the teaching bit before answering the questions?

As Frendo says, think of it as an inequality.

Original poster
Orangeplastic · 24/10/2017 11:09

Ok so ds gave an the lower bound as 44.5kg which was marked correct.

And he gave 45.49 recurring for the upper bound, which was marked incorrect, the teacher wrote 45.5 as the correct answer.

I would have thought if the child weighed 45.5Kg it would have been rounded up to 46kg not rounded down to 45kg?

OP posts:
MirandaWest · 24/10/2017 10:42

What answer was he told was correct?

TheFrendo · 24/10/2017 10:41

Best written as an inequality

45.5

OhYouBadBadKitten · 24/10/2017 10:29

well, no others said actually apart from MustTidyUp.

OhYouBadBadKitten · 24/10/2017 10:28

As TheFallenMadonna and others have said.

MongerTruffle · 24/10/2017 10:27

His weight is not 45 kg. His weight on Earth is 441 N.

His lowest possible mass is 44.5 kg. His highest possible mass is 45.49 with the 9 recurring.

Allthebestnamesareused · 24/10/2017 10:26

44.5 and 4.499r

MustTidyUpMustTidyUp · 24/10/2017 10:24

As above - a value of 45.5 would actually round up but it’s the closest number we can use to 45.49recurring. So we use this as the upper bound.

leonardthelemming · 24/10/2017 10:23

Being a total pedant here, but the question is incorrectly worded. It should say "Joe's mass was 45 kg."

TheFallenMadonna · 24/10/2017 10:22

44.5. 45.5

HKW81 · 24/10/2017 10:18

44.51 kg or 45.49 kg

NoCryLilSoftSoft · 24/10/2017 10:18

Lowest 44.5kg? Highest 45.49999kg?

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