Why is the average IQ 100?

Answer 1

No, 68 percent of the world's population has an IQ of between 90 and 110, an IQ of 120 means that about 95 percent of the world's population is below that point in IQ. An IQ of 100 is average.

Answer 2

Because IQ is calculated by dividing a person's mental age (determined by the IQ test) by their chronological age, then multiplying by 100. Therefore, if your mental age is equal to your chronological age, you will have an IQ of 100.

IQ = Mental age / chronological age x 100

For example:

• A five-year-old has a chronological age of five, and a 60-year-old has a chronological age of 60. If the five-year-old's mental age is also five, and the 60-year-old's mental age is 60, then they both have an IQ of 100:
  • 5/5 x 100 = 100 (average IQ - "on age level"). 60/60 x 100= 100
• If the 60 year old had a mental age greater than his chronological age (60), let's just say 70, then his IQ would be greater than 100. His mental capacity is greater than what it should be, given his age.
  • 70/60 x 100 = 117
• If the 60-year-old had a mental age less than his chronological age, such as 50, then his IQ would be lower than 100. His mental capacity is lower than what it should be, given his age.
  • 50/60 x 100 = 83

Answer 3

Yes, 100 is the average IQ score.