Explain how the Full Scale IQ is lower than all the Index scores?

The Full Scale IQ (FSIQ) can be lower than individual Index scores due to the way it is calculated, incorporating a broader range of cognitive abilities. While Index scores reflect specific domains of intelligence, the FSIQ averages these scores, potentially diminishing the impact of exceptionally high scores in certain areas. Additionally, variations in test performance, such as lower scores in working memory or processing speed, can disproportionately affect the overall FSIQ. This can result in a scenario where the FSIQ does not fully represent the individual's cognitive strengths as indicated by the Index scores.