https://www.gregmat.com/quizzes/quiz/timed-quant-section-15-questions-hard-12 (Question 7)
the question asks in the 2nd condition that “mean greater than 16”, but by taking 17.6 it gives exactly 16 not greater than 16. so shouldn’t the answer be option of “20”
You make a good point but notice the question used “approximate”.
Check out below quote from the solution.
“Some students have asked us why the answer is not D - notice that the question says “approximate” - and the minimum value that satisfies the condition is very close to option C”