The builder casts a [[$ 5.0 \;\text{m} $]] long and [[$ 5.0 \;\text{m} $]] wide concrete slab with a thickness of [[$ 10 \;\text{cm} $]]. He mixes the concrete himself using the following volume ratio: cement [[$ 1 $]], sand [[$ 5 $]] and water [[$ 3 $]]. How many [[$ 40\;\text{kg} $]] sacks of cement does the builder need? The specific density of cement is here [[$ 1,34 \;\text{kg/dm}^3 $]]. (Source: Finnish matriculation exam, autumn 1995)

Take a picture of your solution and return it to the submission folder.

Answer: sacks are needed.