TASK DEFINITION: In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.
PROBLEM: New species are believed to arrive in the Mediterranean at the rate of _ to five annually.

SOLUTION: four

PROBLEM: Perennial grass takes _ to five years before it is mature enough to produce adequate seed.

SOLUTION: three

PROBLEM: Animals fall into _ categories based on their diet.

SOLUTION:
three