A $z-$score of $z=-1\mathrm{.}50$ indicates that the raw score occupies what position in a distribution? a$)1\mathrm{.}5$ points above the mean b$)1\mathrm{.}5$ standard deviations above the mean c$)1\mathrm{.}5$ points below the mean d$)1\mathrm{.}5$ standard deviations below the mean