Question

100, 50, 33.33, .............., 20

• A. 25
• B. 30
• C. 22
• D. 21

Hint:

When decimals like 33.33 appear in a series with 100 nearby, test the form \( \frac{100{n \) (or percentages of 100). It often reveals a neat harmonic-type pattern.

Answer 1

The Correct Option is A

To identify the next number in the sequence 100, 50, 33.33, ..., 20, we need to recognize the pattern. Notice that:

• The sequence decreases from 100 to 50, which is a reduction by the half of 100: 100 - 50 = 50.
• Then, from 50 to 33.33, it reduces by 16.67 (approximately one-third of 50).
• The next number should follow a pattern of proportional decrease.

Calculating step-by-step:

• The first difference: 100 - 50 = 50.
• The second difference: 50 - 33.33 = 16.67.

First Term	Difference	New Term
100	-50	50
50	-16.67	33.33
33.33	-13.33	20

• The missing number is calculated using proportional decrease:

33.33 - 13.33 = 20.00

• Next logical value after 33.33 should add up to the next complete pattern leading to 20. Thus, the answer should be 25.

Hence, the missing number is 25, giving the sequence: 100, 50, 33.33, 25, 20.