Some SAT I Math Problems that I don't know how to solve.

convexity
Fri, 27 Nov 2009 21:25:10 +0000

Harmonic mean. [This should help.](Statistics/Summary/Averages/Harmonic Mean - Wikibooks, open books for an open world)
If the number belongs to both sets, then it should be be a positive multiple of 6 AND a multiple of 8 (i.e. a multiple of the LCM of the two) and less than 50.
Combination. [This should help.](Easy Permutations and Combinations – BetterExplained)
30 < x < 34 <=> -2 < x - 32 < 2 <=> |x - 32| < 2. Or just try plugging in x = 33.9.