Given that intelligence quotient (IQ) scores are normally distributed with a mean of 100 and a standard deviation of 15, which of the following statements is accurate?

IQ scores theoretically have no upper limit, although scores above a certain range are rare. The mention of 145 does not represent a maximum but rather a high score within the range of possible IQs, making this statement inaccurate.

While both scores are valid, they are not equally likely due to their positions relative to the mean. An IQ of 70 is significantly lower than the mean, while 130 is above it; the normal distribution shows that scores closer to the mean (100) are more frequent than those further away, thus making this statement incorrect.

The mean IQ score is defined as 100 in this context, so stating that the average is 115 is incorrect. The average, or mean, is central to the distribution and does not shift unless specified otherwise.

In a normal distribution, scores near the mean (100) are more likely to occur than those further away. Since 85 is one standard deviation below the mean, it is more common than 115, which is slightly above the mean, making this statement false.