Since the beginning of the twentieth century, the human population of the Earth has approximately how many times increased?

Introduction / Context:
The growth of the human population of the Earth during the twentieth century is a classic topic in world geography and general knowledge. Understanding how many times the population has increased provides context for questions of resource use, urbanisation, environmental pressure, and development planning. Examinations often test an approximate multiple rather than an exact number, because population values change gradually and are usually remembered as rounded figures rather than precise counts.

Given Data / Assumptions:

• Turn of the century refers to the beginning of the twentieth century, around the year 1900.

• World population around 1900 is commonly taken as roughly 1.5 to 1.7 billion people.

• Around the end of the twentieth century, world population is commonly taken as roughly 6 billion people.

• The question expects an approximate multiple, not an exact mathematical ratio.

Concept / Approach:
The idea is to compare the approximate population at the beginning of the twentieth century with the approximate population at the end of that century. If the later value is about three times the earlier value, then we say that the population has roughly trebled. The focus is on long term demographic trends rather than short term fluctuations, and on orders of magnitude rather than exact numbers.

Step-by-Step Solution:
Step 1: Take the approximate world population around 1900 as about 1.6 billion people. Step 2: Take the approximate world population around the year 2000 as about 6 billion people. Step 3: Form an approximate ratio by dividing 6 by 1.6, which gives a value a little below 4. Step 4: Since the growth is clearly more than double but less than four times, the closest rounded description is that the population has roughly trebled. Step 5: Therefore, among the given options, the best representation of this long term increase is the option that says roughly trebled.

Verification / Alternative check:
Another way to verify the idea is to remember widely quoted textbook facts that world population crossed 2 billion around the 1920s, 3 billion around 1960, 4 billion in the mid 1970s, 5 billion in the late 1980s, and 6 billion by the end of the 1990s. All of these milestones confirm that the twentieth century saw an increase from well below 2 billion to about 6 billion. This supports the statement that population has become roughly three to four times larger, and for a simple multiple based question, trebled is considered the standard approximate answer.

Why Other Options Are Wrong:

• Stayed approximately the same is wrong because the population has grown dramatically and clearly has not remained constant.

• Roughly doubled is an underestimate because the increase is clearly more than two times.

• Increased about ten times is a serious overstatement, because a tenfold increase from 1.6 billion would mean around 16 billion people, which is far above observed values.

Common Pitfalls:
Students sometimes confuse the twentieth century with the twenty first century, or rely on very recent population figures such as more than 7 billion and then misjudge the multiple. Others think in terms of rough impressions such as huge growth and may incorrectly jump to ten times. The key is to recall standard textbook milestones and to remember that a change from about 1.6 billion to about 6 billion means a multiple slightly below four, which is best described as roughly three times for the purpose of this type of question.

Final Answer:
The approximate increase is best described as Roughly trebled.