Yesterday, Manhattan GMAT posted a GMAT question on our blog. Today, they have followed up with the answer:
To ensure that we grasp the four definitions, we might restate them—taking care to preserve the meaning precisely.
O(x) rounds x up to the nearest odd integer, whereas o(x) rounds x down to the nearest odd integer. The two E-functions do the same thing, except that the outcome is even integers.
Now let’s write the terms one at a time and apply the functions.
O(3.2) = 5 (notice that we must round up pretty far)
E(–1.7) = 0 (remember that the 0 is larger than –1.7)
o(–1.3) = –3 (we have to round down pretty far, and –3 is less than –1.3)
e(2.7) = 2
5 + 0 + (–3) + 2 = 4
The correct answer is (C).