Gross profit method

The inventory was destroyed by fire on December $31.$ The following data were obtained from the accounting records:

Jan. $1$

Jan. $1-$ Dec. $31$

Inventory

Purchases $($net$)$

Sales

Estimated gross profit rate

$$350,000$

$2,950,000$

$4,440,000$

$35\%$

a$.$ Estimate the cost of the inventory destroyed.

Estimated Cost of Merchandise Destroyed

b$.$ Which method is used to estimate inventory cost in case of inventory destroyed by fire?