Look at this series: XXIV, XX, __, XII, VIII, ... What number should fill the blank?

Two series alternate here, with every third number following a different pattern. In the main series, 3 is added to each number to arrive at the next. In the alternating series, 5 is subtracted from each number to arrive at the next.

In this series, the letters progress by 2, and the numbers increase by 2.

This series alternates the addition of 4 with the subtraction of 3.

In this simple addition with repetition series, each number in the series repeats itself, and then increases by 12 to arrive at the next number.

This is a simple subtraction series in which a random number, 93, is interpolated as every third number. In the subtraction series, 10 is subtracted from each number to arrive at the next.

This is a simple multiplication series. Each number is 2 times greater than the previous number.

In this series, the letters progress by 1; the numbers decrease by 3.

The wing, fin, and rudder are all parts of an airplane.

The core, seeds, and pulp are all parts of an apple. A slice would be a piece taken out of an apple.

A peninsula, island, and cape are all landforms; a bay is a body of water.