help me for 2 questions

1. (1) Write down the formula for the mean of a data set. (i) Write down the formula for the standard deviation of a data set. Using an appropriate table, find (ii) The mean for the following data set. (iv) The standard deviation for the following data set. (v) The median and the mode for the following data set. Data Set 21 25 26 30 30 33 35 36 37 2. A sample of 50 first year economics students shows their expenditure on books as follows: Expenditure Number of (E) students 0-under 20 1 20 - under 40 12 40 - under 60 17 60-under 80 16 80-under 120 4 Using an appropriate table (a) Calculate and interpret the mean of the expenditure on books. (b) Calculate and interpret the median of the expenditure books. (c) Calculate and interpret the modal class for the expenditure on books. (d) Calculate and interpret the standard deviation of the expenditute on books. (e) Calculate and interpret the quartiles (Q, QAQ:) (0) Calculate the interval (1-2, 7+2s)