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HOW IS THE ANSWER 89.050

4.337 ONLY HAS 4 SIGNIFICANT FIGURES

ISNT IT SUPPOSE TO BE 89.05 ONLY

HOW PLS ALL THE ANSWERS SAY 89.050

AsadRehman Apr 25, 2020

edited by
Guest
Apr 25, 2020

#1**+2 **

The answer is 89.050 becuase

84.7128

+ 4.337

---------------

89.0498

The rule of adding for sig figs is that since 4.337 has 3 digits after the decimal point, the sum has to have 3 digits after the decimal point also.

So, we can disregard the last 8 and we get 89.049. Now, we round it and since 8>5, and 9>5, the final answer is 89.050.

Here's a good video that really helps: https://www.youtube.com/watch?v=l2yuDvwYq5g

(Please watch it! It's really really helpful! You should start the video at **13:00** because that's where it talks about addition)

I hope this helped you, guest!

If you have any questions, don't hesitate to ask!

:)

lokiisnotdead Apr 25, 2020

#3**0 **

Hi loki,

As i have said below, you are confused about this.

But I have not looked at your video yet, I will do that now.

.....

Ok I have looked at it from 13:00 as you suggested. The addition part is really good.

I have not looked at all of it but it is long, and based on what I did see, I assume it is an excellent reference for significant figures.

Thanks for giving guest the link. I think guest should watch it.

Guest if it says anything that sounds wrong, fire your doubts at us here.

Melody
Apr 25, 2020

#2**+1 **

Hi guest, it is good that you are trying to get this sorted.

Significant figures can be quite confusing. Mostly if you use your logic rather than a calculator, you will get it correct.

I was about to say that the answer is wrong. **But it is not.**

You have to understand significant figures, I would be dubious about trusting a sig fig calc, but this time they are right.

-------------------------------

Loci, thanks for answering but I am afraid you are a bit confused. The 8 and the 9 have absolutely nothing to do with the rounding.

-------------------------------

Let's look at this:

By itself 4.337 has 4 significant figures. That is true.

and taken alone 81.7128 does have 6 significant figures, that is true too.

If we __multiplied__ the 2 the answer would have 4 significant figures. That is true too.

However, we are adding.

When considered together they both have a significant 10s value. For the first number it is 0, and for the second number it is 8.

So the digits for both are significant up to the thousandth place. When added the significant answer will be 89.050 the value in the thousandths place will continue to be significant.

Here are 2 more examples.

You have a piece of wood that is 5 metres long and another piece that is 5 mm long.

If you just add then you get a length of 5.005m long.

This is nonsense.

Both the original values have 1 significant figure so it makes sense for the final answer to have only 1 significant figure.

So your resultant length of wood is 5 metres long.

However:

You have a piece of wood that is 5.0002 metres long and another piece that is 5 mm long.

If you just add then you get a length of 5.0052m long.

BUT

Both the original values are significant to the nearest mm so it makes sense for the final answer to be significant to the nearest mm

So the resultant significant answer is 5.005

Melody Apr 25, 2020