$3.(6$ points$)$ Over the past year, Mountains Manufacturing had annual sales of $10,000$ insulated window sets. Average quarterly sales have been: spring $4,000,$ summer $3,000,$ fall $2,000,$ and winter $1,000.$ Compute the quarterly index. Then assuming there is an expected $10\%$ increase in sales next year, compute annual sales and quarterly sales for the next year.