Ageologist finds four layers of sedimentary rock. she determines that no geologic events have shifted the layers. she labels the layers a, b, c, and d from the top to the bottom. which statement about these layers is accurate? a is older than b. b is older than c. c is younger than a. b is younger than d.

The answer is; B is younger than D

In sedimentary rocks, the bottom layers are older that overlaying layers. This is because sediments are placed on top of each other by surface runoffs to ocean beds. Therefore, the first sediments to be deposited will always be towards the bottom as more and newer ones are brought in and deposited.

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.