Final answer:
Using the regression model, the predicted sales for day 60 would be 250.12 thousand dollars and for day 90 would be 324.52 thousand dollars.
Step-by-step explanation:
To predict the sales growth for an electronics retailer, we can use the provided linear regression model ŷ = 101.32 + 2.48x, where ŷ represents the predicted sales in thousands of dollars and x is the day within the first quarter. For day 60, we substitute x with 60 to get ŷ = 101.32 + 2.48(60) which equals 101.32 + 148.8, resulting in a prediction of 250.12 thousand dollars. Similarly, for day 90, the prediction would be ŷ = 101.32 + 2.48(90), which equals 101.32 + 223.2, resulting in a prediction of 324.52 thousand dollars.