Final answer:
The probability of choosing a vowel from the word 'EXTRATERRESTRIAL' is 2/5 or 40%.
Step-by-step explanation:
To find the probability of choosing a vowel from the word 'EXTRATERRESTRIAL', we need to determine the number of vowels in the word and divide it by the total number of letters in the word. The word 'EXTRATERRESTRIAL' has 6 vowels (E, A, E, E, I, A) and a total of 15 letters. So the probability of choosing a vowel is 6/15, which can be simplified to 2/5 or 40%.