Respond to this Question
Similar Questions

Astronomy  help!
The earliest fossil records indicate that life appeared on Earth about a billion years after the formation of the solar system. What is the most mass that a star could have in order that its lifetime on the mainsequence is long
asked by anonymous on October 29, 2008 
Physics  Half Life Question Check!!!
An ancient rock is found to contain 40Ar gas, indicating that 77% of the 40K in the rock has decayed since the rock solidified. Any argon would have boiled out of liquid rock. How long ago did the rock solidify? The halflife of
asked by Meli on April 28, 2015 
Earth Science
1. We start with 400 atoms of Uranium238. How many remain after 4.5 billion years? _______ After 9 billion years? _______ After 13.5 billion years? ________ 2 . How long will it take for ½ of the original amount of Rubidium87
asked by 아, 깹송~ on February 8, 2017 
Math/Radioactive Dating
My teacher said that if the ratio of mass (in a rock) for 40K and 40Ar was 1:3 then the age of the rock would be 2.5 billion years. I don't understand how he concluded that to be the age. The only thing he knew was that the
asked by Lena on February 19, 2011 
geology
How old are the oldest meteorites yet studied and what is the minimum age of Earth since Earth is at least as old as the meteorites. We know the oldest meteorites contain equal amounts of uranium 238 and lead 206. Uranium 238 has
asked by m on November 21, 2010 
business math
If Naomi decides that she will invest $3,000 per year in a 6% annuity for the first ten years, $6,000 for the next ten years, and $9,000 for the next ten years, how much will she accumulate? Treat each ten year period as a
asked by Heather on April 5, 2010 
Astronomy
At what cosmic time was/is star formation density at its peak? At present time. Within the first billion years after the Big Bang. At about few billion years after the Big Bang. About few billion years ago.
asked by qwerty on March 11, 2013 
Math
What place value is ten times smaller than ten millions place? A) hundred trillion B) one trillion C) hundred billion D) ten billion I think it's ones place. But that's not an option, maybe they did a typo.
asked by Jazmin on November 27, 2011 
Math (fibonacci
A sequence of numbers is called a Fibonaccitype sequence if each number (after for the first two) is the sum of the two numbers which precede it. For example, 1, 1, 2, 3, 5, 8 ... is a Fibonacci type sequence. If 1985, x, y, 200
asked by Lexmo on August 8, 2014 
Chem 2
The halflife for the radioactive decay of U238 is 4.5 billion years and is independent of initial concentration. a) How long will it take for 10% of the U238 atoms in a sample of U 238 to decay? b)If a sample of U238
asked by Kristina on July 21, 2011