can you help me to find the z and slope

The average annual cost of tuition of 1,500 college students in top private universities in a certain city is Php 160,000. With the assumption that the annual costs of tuition are normally distributed with a standard deviation of Php 15,000, 1. an educator randomly selected 45 private top private university students. What is the probability that the mean annual cost of tuition of the sample will be more than Php 125,000? 2. find the number of students who spend from Php 80,000 - Php 105,000 annual tuition fee 3. how many of them spend less than Php 120,000 annual tuition fee? 1. The amount of time that the 1, 670 students in a university spend in research per week is normally distributed with a mean of 15 hours and a standard deviation of 2.7 hours. What is the probability that a 30 randomly selected students engage in research which is: 1. equal to or more than 8 hours per week? 2. more than 6 hours but less than 12 hours per week 3. less than 10 hours per week