vocab problem

A student studying for a vocabulary test knows the meanings of 10 words from a list of 26 words. If the test contains 10 words from the study list, what is the probability that at least 8 of the words on the test are words that the student knows? (Round your answer to three decimal places.)

(10 C 8 + 10 C 9 + 10 C 10)/(26 C 10)?? I feel like I'm missing something with 10 with 8 words on test?

\(\displaystyle \sum_{k=8}^{10}\frac{\binom{10}{k}\binom{16}{10-k}}{\binom{26}{10}}\)