The company "TRAMAD" is conducting a study on the variation of the prices of its shares, listed on the Santiago Stock Exchange. For this purpose, it takes a sample of prices corresponding to the last 30 working days. The value indicated is the one that has been registered at the closing time of the operations:

450540280440350720400190410700

600500250780290580320220320660

300360320605180300210520290420

a) Make a frequency table.

b) TRAMAD estimates that your situation is not alarming if the percentage of days in which prices were less than or equal to $400 is less than 30%. What do you say Is this company's situation alarming or not? Explain.

c) Calculate the mean and standard deviation.

d) Calculate and interpret the quartile 1.