A mass is 250 g to the nearest 10 g Step by Step

Step by step

The question

Question: the mass is 250 g, to the nearest 10 g.

Find the upper and lower bounds.

Mass: 250 g, to the nearest 10 g

The real mass was rounded.

We want the smallest and the biggest it could have been.

1 Find the step

It was rounded to the nearest 10 g.

So the step is 10 g.

step = 10 g

upper bound = the biggest it could be

lower bound = the smallest it could be

2 Half a step

Anything less than half a step away rounds to 250.

Half of 10 is 5.

half a step = 10 ÷ 2 = 5 g

3 Find the bounds

The lower bound is 250 minus 5: 245.

lower bound = 250 − 5 = 245 g

Careful!

We go only half a step down and half a step up.

240 would round to 240, not to 250.

Careful: not 240 to 260 ✗

The upper bound is 250 plus 5: 255.

upper bound = 250 + 5 = 255 g

4 Show it on a number line

So 245 ≤ mass < 255.

This is called the error interval.

245 ≤ mass < 255

5 Check

Let's check.

245, rounded to the nearest 10 g, is 250.

245 rounds to 250

And 254, just under the upper bound, also rounds to 250.

So the bounds are right!

254 rounds to 250

Let's look back.

First: find the step.

Then: half a step.

Then: find the bounds.

Then: show it on a number line.

Last: check.

Answer