Naturally occurring uranium is composed mostly of 238U and 235U, with relative abundances of 99.28% and 0.72%, respectively. The half-life for 238U is 4.5 * 109 years, and the halflife for 235U is 7.1 * 108 years. Assuming that the earth was formed 4.5 billion years ago, calculate the relative abundances of the 238U and 235U isotopes when the earth was formed.

Naturally occurring uranium is composed mostly of ²³⁸U and ²³⁵U, with relative abundances of 99.28% and 0.72%, respectively. The half-life for ²³⁸U is 4.5 * 10⁹ years, and the halflife for ²³⁵U is 7.1 * 10⁸ years.

Assuming that the earth was formed 4.5 billion years ago, calculate the relative abundances of the ²³⁸U and ²³⁵U isotopes when the earth was formed.