Question

the study hours are 4, 10, 20, 24, 34, 36, 42 and the z scores are 2.5, negative 1.75, negative .5, 0, 1.25, 1.5, 2.25 and the percentile ranks are 10,25,35,40,50,75,95 what is the study hour with a z score of 1.75, what is the standard deviation of all the students, and what the is the study hour 2.5 standard deviations above the mean?