# 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?

### 9 Answers

- GeorgeLv 71 decade agoFavorite 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.

- RamonLv 71 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

- How do you think about the answers? You can sign in to vote the answer.
- Anonymous1 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 :(

- Anonymous1 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

- dophseLv 51 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
percent... divide 2/7 *100 = 28.5% left. 100-28.5=71.5% died. Idk the 1 in how many part.. lol.