You are dating moon rocks based on their proportions of uranium-238 (half-life of about 4.5 billion years) and its ultimate decay product, lead.
1.find the age for a rock for which you determine that 58% of the original uranium-238 remains, while the other 42% has decayed into lead.
t=( ) billion years
2.find the age for a rock for which you determine that 66% of the original uranium-238 remains, while the other 34% has decayed into lead.
t=( ) billion years

1) The rock is 3.78 billion years old.

2) The rock is 3.06 billion years old.

Explanation:

Hi there!

The half-life is the time at which half of a substance in a sample disappears. In this case, half of the uranium of the rocks will disappear in 4.5 billion years.

1) 42% of the uranium has disappeared. Then, if 50% disappears in 4.5 billion years, 42% has disappeared in (42% · 4.5 billion years/50%) 3.78 billion years. Then the rock is 3.78 billion years old.

2) The procedure is the same as above: if 50% of uranium will disappear in 4.5 billion years, 34% has disappeared in (34% · 4.5 billion years/50%) 3.06 billion years. Then, the rock is 3.06 billion years old.

Have a nice day!

i'm pretty sure it is letter c.) car

28528289 29823282 8298232 39858