need help in this problems in probability and statistics, thanksss

The following table shows the number of umbrellas sold by a convenience store from January to October 2020.

(The answer is accurate to 4 decimal places)

Month (month) 1 2 3 4 5 6 7 8 9 10

Average monthly rainfall (mm) 4 68 186 185 234 429 328 596 198 149

Number of umbrellas sold (pieces) 63 274 409 459 545 670 388 773 212 243

(a) Which item is the independent variable? Which is the dependent variable? (2 minutes)

(b) Find the sample correlation coefficient (r), and explain the meaning of the value; (4 points)

(c) Write the regression coefficients separately

Values of a and b, and write the fitted regression equation; (3 points)

(d) Using the regression equation, when the average monthly rainfall is estimated to be 500 mm,

What is the number of umbrellas sold;

(The answer is accurate to the nearest whole number) (2 points)