Below is a table showing some of the results from the analysis described in Exercise 13, where we were attempting to link y, the time that a house listed for sale remains on the market, to the size of the house (x1), the asking price (x2), and the age of the house (x3). Twenty-one houses were included in the sample. Determine which, if any, of the individual coefficients are statistically significant at the 5% significance level.