Uranium-238 (U-238) has a half-life of 4.5 billion years. Geologists find a rock containing a mixture of U-238 and lead, and determine that 65% of the original U-238 remains; the other 35% has decayed into lead. How old is the rock? The rock is billion years old. (Round to three decimal places as needed.)A mummy was recently discovered. It now contains 61.6% of its original Carbon 14. About how old is the mummy. Assume that the half-life of Carbon 14 is 5730 years. ROUND YOUR ANSWER TO THE NEAREST YEAR. The mummy is about years old