# Thread: Word Problem

1. ## Word Problem

The planet Earth is 5 billion years old (a billion is one thousand million). Life first evolved on Earth around 4 billion years ago. The species Homo Sapiens is around 1 million years old. Imagine that the 5 billions years of Earth's existence is represented by one single year starting on January 1'st and ending December 31'st.
(a) On what day and roughly at what time on that day do Homo Sapiens first appear?
(Please enter month (write out the word), then date, then time, then am' or pm') What date will it be? , : (b) The earliest civilizations of which we have records are no more than 10,000 years old. What date and time does this corresond to?

2. Hehe, I did this a month ago

5 billion years will be 365 days !
The most direct way is to calculate the difference between Earth's age and the apparition of Homo Sapiens. This would be 4.999 billion years. So divide it by 365 to get the number of days since the 1st of January.

Another way to do this is to start from the end.
You know the ratio date/days (365/5billion), so 1 million will be ... days from the end.