There are 8 red tegu lizards in the reptile house at a local zoo. If the average length of the red tegu lizards is 10 inches, then how many of the red tegu lizards are exactly 10 inches long?

Answer: number of red ten inch tegu lizard = even number between 0 and 8

Step-by-step explanation: if the average length is 10, assigning 10 to only one lizard won't give us average of ten, it also means assigning 10 to odd number between 1 and 7 inclusive won't give us that average, so it's either it's no lizard with length 10 or even number of lizard between 0 and 8.