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Thread: scientific notation and significant figures ( i don't have a lot of time please! )

  1. #1
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    Sep 2013
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    Unhappy scientific notation and significant figures ( i don't have a lot of time please! )

    This was In my chemistry homework but i cant figure out if im doing it right because there is nothing like it in the book.
    Please help

    Round the following numbers to the specified significant figures and write in scientific notation.
    a. 0.99692 x 10-2 to 3 sig. fig.
    b. 0.03944498 to 2 sig. fig.
    c. 136.050 to 3 sig fig.
    d. 102.50 x 10-13 to 2 sig fig.
    e. 0.0020050001 to 3 sig. fig.
    f. 0.4975000 to 3 sig fig.

    What i got
    a.9.97 x 10^-3
    b. 4.0 x 10^-2
    c. 1.360 x 10^2
    d. 1.02 x 10^-15
    e. 2.00 x 10^-3
    f. 4.98 x 10^-1

    there is also a rule we follow that says "if the next digit is 5 or followed by only zeros then a)if the number before is even then retain the previous digit b)if its odd then increase previous digit by one"

    ex 1.27500 =1.28
    ex 1.28500 =1.28
    ex 1.9950 = 2.00
    ex 19850 = 1.98

    thank you for your help!

  2. #2
    Elite Member
    Join Date
    Jun 2007
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    17,481
    Quote Originally Posted by Dray View Post
    This was In my chemistry homework but i cant figure out if im doing it right because there is nothing like it in the book.
    Please help

    Round the following numbers to the specified significant figures and write in scientific notation.
    a. 0.99692 x 10-2 to 3 sig. fig.
    b. 0.03944498 to 2 sig. fig.
    c. 136.050 to 3 sig fig.
    d. 102.50 x 10-13 to 2 sig fig.
    e. 0.0020050001 to 3 sig. fig.
    f. 0.4975000 to 3 sig fig.

    What i got
    a.9.97 x 10^-3
    b. 4.0 x 10^-2 ← 3.9 * 10-2
    c. 1.360 x 10^2 ← 1.36 * 102
    d. 1.02 x 10^-15← 1.0 * 10-15
    e. 2.00 x 10^-3
    f. 4.98 x 10^-1

    there is also a rule we follow that says "if the next digit is 5 or followed by only zeros then a)if the number before is even then retain the previous digit b)if its odd then increase previous digit by one"

    ex 1.27500 =1.28
    ex 1.28500 =1.28
    ex 1.9950 = 2.00
    ex 19850 = 1.98

    thank you for your help!
    .
    “... mathematics is only the art of saying the same thing in different words” - B. Russell

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