In table tennis, what is the standard diameter of an official ping pong ball used in international competitions?

Introduction / Context:
This question deals with basic equipment specifications in the sport of table tennis. Even though it looks like a small detail, the standard size of the ball is defined by official rules and has an impact on the speed and spin of the game. Sports general knowledge questions often test such measurements to see whether candidates are familiar with international standards, not just player names or match results.

Given Data / Assumptions:
• The game mentioned is table tennis, commonly called ping pong.
• The question asks about the standard diameter of an official ball used in international level matches.
• The options are given in millimetres and are close to each other, which means approximate guessing is risky.
• We assume modern regulations, where the current international standard is already in place.

Concept / Approach:
Originally, table tennis balls were 38 mm in diameter, but the International Table Tennis Federation later changed the official size to 40 mm to slightly slow the game and improve visibility for spectators and television. Therefore, the current standard ball used in official international competitions has a diameter of 40 mm. Remembering that there was a change from 38 mm to 40 mm helps you select the correct answer in this type of question.

Step-by-Step Solution:
Step 1: Note that the question refers to the standard diameter of an official ping pong ball, not any casual training ball.Step 2: Recall that the ball size was increased from 38 mm to 40 mm as part of rule changes aimed at making rallies slightly slower and more visible.Step 3: Look at the options and identify 40 mm as the modern standard size.Step 4: Eliminate nearby values like 37 mm and 38 mm, which may tempt you if you remember only the older standard.

Verification / Alternative check:
An easy way to verify is to think about how often you see the number 40 attached to modern table tennis balls and coaching material. Official rule books and equipment packaging for tournament grade balls clearly mention the 40 mm size. Many sports articles explicitly state that the ball size was changed from 38 mm to 40 mm to alter the pace of the game. This confirms that 40 mm is the correct and up to date standard for international play.

Why Other Options Are Wrong:
• 37 mm is smaller than both the old and new official sizes and does not correspond to any recognised standard.
• 38 mm was the old official diameter before the rule change; it is no longer the current standard specified in the question.
• 42 mm is larger than the official size and would significantly change the way the game is played.
• 36 mm is even smaller and is not used in regulated table tennis competitions.

Common Pitfalls:
Candidates often remember that 38 mm was once used and may quickly select it without considering that rules have been updated. Others may simply guess a round figure without real knowledge. Confusion between radius and diameter can also mislead some students, but the question clearly states diameter in millimetres. To avoid these mistakes, regularly revise key equipment dimensions in sports where governing bodies have made changes over time.

Final Answer:
The correct answer is 40 mm, which is the standard diameter of an official table tennis ball used in international competitions today.