On an average, \(\tfrac{1}{10}\) of the food eaten becomes available to the next level in a food chain. What fraction of the food eaten is not available for the next level?
\(\dfrac{9}{10}\)
We are told: on average, \(\tfrac{1}{10}\) of the food eaten moves to the next level of the food chain.
Think of the total food eaten as one whole:
\(1\)
Part that goes to the next level:
\(\tfrac{1}{10}\)
So, the part that is not available for the next level is:
\(\text{Total food} - \text{Food passed on}\)
\(1 - \tfrac{1}{10}\)
Write both with the same denominator:
\(\tfrac{10}{10} - \tfrac{1}{10} = \tfrac{9}{10}\)
Therefore, the fraction not available for the next level is:
\(\boxed{\tfrac{9}{10}}\)
(In words: nine-tenths of the food is not available for the next level.)