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#### Christian Lawson-Perfect2 years, 8 months ago

Saved a checkpoint:

I've split parts a and b into separate questions. I'm not sure about part c - is it obviousthat you'd always want to underestimate the distance? Maybe it needs a sentence like "you want to know if you'll meet your target in the next five minutes".

#### Christian Lawson-Perfect2 years, 8 months ago

Gave some feedback: Should not be used

Published this.

#### Stanislav Duris2 years, 9 months ago

Saved a checkpoint:

Vicky suggested making this question and these parts because she thought the other question about estimation was not applicable to real life estimation enough. If this question still needs some stuff to do and someone else picks it up after I leave, you can maybe change some of the scenarios or adjust the question so there is no specific rounding students need to do and they can just choose one they want as Christian suggested. I sadly do not have time for this.

#### Stanislav Duris2 years, 9 months ago

Gave some feedback: Needs to be tested

#### Christian Lawson-Perfect2 years, 9 months ago

Gave some feedback: Has some problems

#### Christian Lawson-Perfect2 years, 9 months ago

Saved a checkpoint:

There are too many items in part a - I can't add them all up in my head. Just two or three items, plus the ice cream, would be enough to get the idea across.

Both parts a and b have this problem - even after rounding, I can't do these calculations in my head, so I might as well use a calculator.

"The dimensions of the room are 6.49m×2.88m×3.39m where 3.39m is the height." is oddly worded. I'd say "The room measures 6.49m×2.88m, and 3.39m high."

In part b, I'd round to the nearest metre and do the calculation in my head. My maximum error when rounding to the nearest metre is $4 \times \left(\frac{1}{2}(\text{width}+\text{depth}+\text{height})+\frac{1}{4} \right)\text{m}^2$, which will be around one bucket's worth.

By the way, the height I got, 3.39m, is completely unrealistic! In the UK the minimum ceiling height is 2.1m and the standard is around 2.4m.

The thesis of this question is that sometimes rounding to 1 sig fig is too blunt, but I don't think the given scenarios make a great case for it: they're all 'mental maths' scenarios. If I'm going to use a calculator, I might as well type in 2 decimal places rather than rounding to 1. Can you think of scenarios where you've got some very precise measurements, but only want a moderately precise answer?

You could use the separate minimum and maximum accepted value settings for number entry parts in a question like this - accept anything within a generous bound of the true answer, and let the student perform whatever estimation they like, maybe guiding them towards one.

#### Stanislav Duris2 years, 9 months ago

Gave some feedback: Needs to be tested

#### Stanislav Duris2 years, 9 months ago

Created this.
Rounding and estimating calculations 2 Should not be used Stanislav Duris 20/11/2019 14:42
Stanislav's copy of Rounding and estimating calculations 2 Should not be used Stanislav Duris 04/07/2017 14:36
Rounding and estimating calculations - adding up prices in a shop Ready to use Christian Lawson-Perfect 20/11/2019 14:42
Rounding and estimating calculations - painting a room Ready to use Christian Lawson-Perfect 20/11/2019 14:42
Consumer Arithmetic - Rounding and estimating calculations - adding up prices in a shop draft Paul Hancock 24/07/2018 03:04
David's copy of Rounding and estimating calculations - painting a room draft David Rickard 07/11/2018 21:04

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