In an attempt to motivate their son to work harder in school, Abe’s parents begin paying to finish reading his books. They do not pay him at the end of each book, but his pay is equal to an average of $5 for every 3 books that he completes. What type of reinforcement schedule is this? Group of answer choices

fixed-interval

fixed-ratio

variable-interval

variable-ratio

i need an image of the diagram

it's diluted or concentrated

in a diluted solution, you can add a lot more solute but in concentrated only a little more can be added

they have identical fossils of organisms that have evolved over time.

both have animal fossils preserved in them due to weathering and erosion.

they contain different fossils because life on earth has changed through time.

the fossils in them were formed on the surface of earth due to exposure to sunlight.