Suppose an igneous rock contains 1/64 of its original amount of a parent atom with a half-life of 29 million years. How many half-lives have passed since the formation of the rock and how old is the rock? 64 half-lives and 57,4 milition vears oild 32 hait-lives and 928 million yeais ald 8 half-fives and 232 million vears old 7 talf-lives and 4.14 milion vean old 6 huit lives and 174 million vears old 5.silf-eves and 5.A mulion yres 4 hatf-lives and 116 million vears 2 hatf lives and 14.5 milion year 2 talf-kres and 28 million year.