Results 1 to 4 of 4

Math Help - Which Number?

  1. #1
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    Which Number?

    In which number is 72 meters per hour expressed as kilometer per hour?

    (a) 7.2 x 10^(-2)

    (b) 7.2 x 10^(2)

    (c) 7.2 x 10^(-3)

    (d) 7.2 x 10^(3)

    Although it is multiple choice, I want to know how to find the answer.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Behold, the power of SARDINES!
    TheEmptySet's Avatar
    Joined
    Feb 2008
    From
    Yuma, AZ, USA
    Posts
    3,764
    Thanks
    78
    Quote Originally Posted by magentarita View Post
    In which number is 72 meters per hour expressed as kilometer per hour?

    (a) 7.2 x 10^(-2)

    (b) 7.2 x 10^(2)

    (c) 7.2 x 10^(-3)

    (d) 7.2 x 10^(3)

    Although it is multiple choice, I want to know how to find the answer.
    In general here is the idea

    If you have some number with units like this

    a\frac{meters}{hour}

    Note the conversion factor 1000meters= 1 kilometer

    a\frac{meters}{hour}\cdot \frac{1 kilometer}{1000 meters}=a\frac{kilometers}{1000hour}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Mar 2007
    Posts
    1,240

    Talking

    Quote Originally Posted by magentarita View Post
    Although it is multiple choice, I want to know how to find the answer.
    To learn how to convert between metric units, try here.

    To learn how to convert decimal values into scientific notation, try here.

    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Jan 2009
    Posts
    591
    Quote Originally Posted by magentarita View Post
    In which number is 72 meters per hour expressed as kilometer per hour?

    (a) 7.2 x 10^(-2)

    (b) 7.2 x 10^(2)

    (c) 7.2 x 10^(-3)

    (d) 7.2 x 10^(3)

    Although it is multiple choice, I want to know how to find the answer.
    You want to express 72 meters as so many parts of a kilometer.

    Since there are 1000 meters in a kilometer you will need to divide 72 by 1000 to get the meters into kilometers. Then convert it to scientific notation.

    Actually the easy way is to shift the decimal point in the choices given:

    Code:
     
    (a) 7.2 x 10^(-2) =   0.0720
    (b) 7.2 x 10^(2)  = 720.0000
    (c) 7.2 x 10^(-3) =   0.0072
    (d) 7.2 x 10^(3)  =7200.0000
    With minimal thinking you can determine the correct answer.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: January 16th 2012, 02:21 AM
  2. Replies: 4
    Last Post: April 28th 2011, 07:20 AM
  3. Replies: 2
    Last Post: August 19th 2010, 10:32 PM
  4. Replies: 2
    Last Post: December 18th 2008, 06:28 PM
  5. Replies: 5
    Last Post: October 7th 2008, 01:55 PM

Search Tags


/mathhelpforum @mathhelpforum