Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Complicated math problem for other purposes?

ok this is for a novel..

say there are 7 billion people on earth and 'something' like a sickness happens and then there are only 2 billion left on earth. what percent would be left on earth and what percent would have died? also, 1 in how many people would die?

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  • George
    Lv 7
    1 decade ago
    Favorite Answer

    First question: % left on earth. 2 billion divided by 7 billion = 2/7 = .2857 = 28.57%.

    Second question: % died. 5 billion died out of 7 billion = 5/7 = .7143 = 71.43%. You could also subtract 28.57% from 100% to get 71.43%.

    If 5 out of 7 died, then set up a ratio: 5/7 = 1/X where X is the answer. Cross multiply to get:

    5X = 7. X = 7/5 = 1.4. 1 out of 1.4 people died.

    Source(s): Self
  • 1 decade ago

    To figure out what percentage, there is a simple equation:

    (part/whole)=(percent/100)

    The part is 2 billion (or the part of the original number that is left) and the whole is 7 billion. This would end up being written like:

    2,000,000,000/7,000,000,000=x/100

    You would then cross multiply, giving you:

    2,000,000,000(100)=7,000,000,000x multiply 2 billion times 100

    200,000,000,000=7,000,000,000x divide by 7 billion

    x = 28.5714, or 29 % rounded up.

    29% are left, to get the amount that died, just subtract 29 from 100. 100-29 = 71%

    To find 1 in how many people died, first subtract 2 billion from 7 billion to figure out how many people died. This gives you 5 billion. Then take 5 billion and set it over 7 billion in a fraction and reduce.

    This gives you 1 out of every 1.4 people that died. Most statistics aren't written that way, so they would probably say that either: 1 out of every 2 people died, or more accurately, 5 out of every 7 people died.

    So:

    29% of the population is still living

    71% of the population was killed

    5 out of every 7 people died

  • 1 decade ago

    1. percent left on earth

    2. what percent died

    3. 1 in how many die

    1. the percent that are still alive is 2/7 = 28.8%

    2. the percent that died would be 5 billion divided by 7 billion...so about 71.4%

    3. it's not really 1 in something...it's 5 in 7 would die....or you could say something like 1 in 1.4 people would die.

  • Ramon
    Lv 7
    1 decade ago

    percent would be left on earth =(2/7)100=28.6%

    percent would have died =(5/7)100=71.4

    die ( 5 of 7) so

    1 in 1.4 people would die

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  • Anonymous
    1 decade ago

    About 70 percent died which leaves 30 percent who lived. I think that 1 in 3 would have died. Not good with ratios or percents though :(

  • Anonymous
    1 decade ago

    ok, lets start with 1 in how many people died.

    2/7 of the origional population remain, so 5/7 died. this means 1/(7/5), or 1/1.4 people died

    the percent of people left is the same as 2/7*100 = about 28.57% of people remain

    if 28.57% people remain, then the total (100%) - the remaining people (28.57%) is how many people died. 100 - 28.57 = 71.43% of people died

  • dophse
    Lv 5
    1 decade ago

    if you want the percentage from 7 million population

    percentage of people alive (2/7) *100

    and people died (5/7) * 100

    second part

    out of 7 million 5 million died

    in other word

    5 people in in every 7 died

  • 1 decade ago

    left: 2/7 = 0.29 = 29%

    died: 5/7 = 0.71 = 71%

    5/ 7 die or 1 out of 1.4

    .

  • 1 decade ago

    percent... divide 2/7 *100 = 28.5% left. 100-28.5=71.5% died. Idk the 1 in how many part.. lol.

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