Math Is Fun Forum

paulb203

Member

Registered: 2023-02-24

Posts: 323

Truncation

A number x is truncated to 1 decimal place
The result is 6.2
Write down the error interval for x
Answer;
6.2 ≤ x < 6.3

*

Why less than or equal to 6.2? Why the equal to 6.2 part? If x had been 6.2 no truncation would have taken place; nothing would have taken place. The 6.2 just stays the same, no?
We haven’t shortened it. We haven’t chopped off any numbers beyond 1 decimal place; there were no numbers after 1 decimal place.

So why isn’t the answer;
6.2 < x < 6.3 ?
That way we could infer that x was something like 6.21, or 6.2999999999999998, no?

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Bob

Administrator

Registered: 2010-06-20

Posts: 10,627

Re: Truncation

Whoever wrote that answer needs to check the meaning of truncated. I'm with you on this one.

Doubt it'll come up in an exam but if it does I'm sure you'd get full marks.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

KerimF

Member

From: Aleppo-Syria

Registered: 2018-08-10

Posts: 248

Re: Truncation

This is how I understand truncation:
6.20 to 6.2499999 gives 6.2
6.25 to 6.2999999 gives 6.3

Therefore, my answer is:
6.2 ≤ x < 6.25

For instance, the answer [ 6.2 ≤ x < 6.3 ] refers to int(x).

Kerim

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Every living thing has no choice but to execute its pre-programmed instructions embedded in it (known as instincts).
But only a human may have the freedom and ability to oppose his natural robotic nature.
But, by opposing it, such a human becomes no more of this world.

paulb203

Member

Registered: 2023-02-24

Posts: 323

Re: Truncation

Whoever wrote that answer needs to check the meaning of truncated. I'm with you on this one.

Doubt it'll come up in an exam but if it does I'm sure you'd get full marks.

Bob

Thanks, Bob.
That was MathsGenie (which I like a lot).
And it wasn't just one answer; there were a lot of questions with similar set ups, and similar answers.

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Prioritise. Persevere. No pain, no gain.

paulb203

Member

Registered: 2023-02-24

Posts: 323

Re: Truncation

This is how I understand truncation:
6.20 to 6.2499999 gives 6.2
6.25 to 6.2999999 gives 6.3

Therefore, my answer is:
6.2 ≤ x < 6.25

For instance, the answer [ 6.2 ≤ x < 6.3 ] refers to int(x).

Kerim

Thanks, KerimF, but I'm not sure what your first two lines mean.

6.20 to 6.2499999 gives 6.2?

What does that mean?

As I understand it, to truncate means to chop off all the numbers after a certain decimal place, but without rounding.

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Prioritise. Persevere. No pain, no gain.

Bob

Administrator

Registered: 2010-06-20

Posts: 10,627

Re: Truncation

Meaning truncate:

1 | verb | replace a corner by a plane
2 | verb | approximate by ignoring all terms beyond a chosen one
3 | verb | make shorter as if by cutting off
4 | adjective | terminating abruptly by having or as if having an end or point cut off

That means that 6.25 truncated to 1dp is 6.2 not 6.3

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

KerimF

Member

From: Aleppo-Syria

Registered: 2018-08-10

Posts: 248

Re: Truncation

As I understand it, to truncate means to chop off all the numbers after a certain decimal place, but without rounding.

I agree with you.
I usually hear "find the integer' instead of 'truncate'.
I mean, the English math's verb 'truncate' is somehow new to me. Thanks to you, I know now its meaning.

---

Every living thing has no choice but to execute its pre-programmed instructions embedded in it (known as instincts).
But only a human may have the freedom and ability to oppose his natural robotic nature.
But, by opposing it, such a human becomes no more of this world.

paulb203

Member

Registered: 2023-02-24

Posts: 323

Re: Truncation

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Prioritise. Persevere. No pain, no gain.