What is the average price of all products?
select avg ( product_price ) from products
What is the product type of the product whose average price is greater than the average price of all products?
select product_type_code from products group by product_type_code having avg ( product_price ) > ( select avg ( product_price ) from products )
What is the average price of that product with type code Hardware?
select avg ( product_price ) from products where product_type_code = "Hardware"
What is the average price of all products with the type code "clothes"?
select avg ( product_price ) from products where product_type_code = "Clothes"