David I.

asked • 02/06/16

Evaluate to 2 significant figures in standard form (56.739721)squared x 0.0997 ÷ (19787×10 to the power of 3)squared

The solution given for this problem is 8.2×10 to the negative 5.
Please help me in working this out

1 Expert Answer

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Mark M. answered • 02/06/16

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(56.739721)2(0.0997) / (19787 x 103)2
(5.6739721 x 10)2(9.97 x 10-2) / (1.9787 x 107)2
(32.1939594 x 102)(9.97 x 10-2) / (1.9787 x 107)2
(3.21939594 x 103)(9.97 x 10-2 / (1.9787 x 107)2
32.0973775 x 10 / (1.9789 x 107)2
3.20973775 x 102 / 3.91604521 x 1014
0.819637526 x 10-12
8.19637526 x 10-13
 
Well, I agree with the 8.2 and have checked my exponents twice. Then I could have made the same error twice!
 
 
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David I.

Thanks Mark I think the text book I'm using is rounding to 2 sig fig everywhere it can. The other maths problem I have on here is the same but after asking about I believe the text book does have a few mistakes.
 
Thanks for your time!
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02/06/16

Mark M.

David, you are welcome. Recalculated rounding to two significant digits and still get a -13 for the exponent.
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02/06/16

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