# Math Help - Z-test help

1. ## Z-test help

The scores on a university examination are normally distributed with a mean of
62 and a standard deviation of 11. If the bottom 5% of students will fail the
course, what is the lowest mark that a student can have and still be awarded

I can do the questions "going the other way", as it were, but am having terribly difficulty with working backwards for some reason

2. solve for X in.......

${X-62\over 11}=-1.645$

The -1.645 is the bottom 5 percentile point of the st normal.
The integer below that X is an F the integer above that X is the lowest D.