Although there is some controversy regarding the appropriatness of IQ scores as a measure of intellegence, IQ scores are commonly used for a variety of purposes. One commonly used IQ scaled has a mean of 100 and a standard deviation of 15 and scores approximatly normall distributed. One way to become eligible for membership in Mensa, an organization purportedly for those of high intelligence, is to have a Stanford-Binet IQ score of above 130.
I) What proportion of the population would qualify for Mensa membership?
ii) What is the proportion of the population with IQ scores below 80?
iii) What is the proportion of the populaltion with IQ scores between 75 and 125?
iv) Between what values do the IQ scores of the middle 95% of individuals fall?

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I have answered I) to iii)
I am unsure of how to answer question iv). If someone could please help me with it, that would be excellent.

#4: This is asking for the minimum and maximum values of the range that 95% of the population will fall into.

-1.96=\frac{x-100}{15}

1.96=\frac{x-100}{15}

Solve for x in the two equations and that will be the interval.

This means that 95% of the population will fall in this range.

If someone is very smart or very dumb, then they will be in a very low or very high percentile and be outside the range

Thanks heaps for that galactus. What did you get as the final answer to that? Cause I got the equations but my maths is a little rusty.