Average Mental IQ according to Wechsler's Scale is –
Wechsler Adult Intelligence Scale (WAIS) : David Wechsler (1939), published the first intelligence test designed for an adult population; It was the first IQ test based on Normal/Gaussian distribution'.
It is currently in its fourth edition (WAIS-IV). The original WAIS (Form I) was published in February 1955, as a revision of the Wechsler - Bellevue intelligence scale that had been released in 1939. Fourth edition (WAIS-IV) was released in 2008 by Pearson.
The median full scale IQ is Centered at 100, with a standard deviation of 15. In a normal distribution, the IQ range of one SD above and below the mean (i.e. 85 and 115) is where approximately 68% of all adult would fall.
70–79
80–89
90–109
110–119