Given:
μ = 7.5, the population mean
σ = 1.5, the population standard deviation
According to the 68 - 95 - 99.7 rule, 68% of the population data lies within one standard deviation of the population mean.
Therefore the range of sizes that fit 68% of women is
(7.5-1.5, 7.5+1.5) = (6.0, 9.0)
Answer: 6.0 to 9.0