how to solve this with normal cdf or invnorm statement specially and also want to understand about the diagrams in bell shape for the clarification of this question

IQ tests are designed to be normally distributed with a mean of 100 and a standard deviation of 15. a. To join Mensa, a special organization for exceptionally bright individuals, you must have an IQ of at least 138. What percent of the population can join Mensa? b. Many Sociologists consider a child as "gifted" if their IQ is above 150. i. What percent of the population is considered to be gifted? i. If a particular school district contains 12,000 students, then how many of them would you expect to be labeled as being gifted? c. To the nearest whole number, what is the minimum IQ for the top 1% of individuals? d. To the nearest whole number, what is the maximum IQ for the bottom 3% of individuals