Hanna holds a certain number of cards, each of which is green or black or yellow. If a person picked up a card randomly

What we see: a yes-or-no Data Sufficiency question. Is the chance of drawing a black card exactly \(\frac{2}{5}\)? A statement is enough if it gives a sure "yes" or a sure "no."

Step 1. Statement (1): 16 cards in all.
What we see: we know the total but not how many are black.
What it means: for the chance to be \(\frac{2}{5}\), the black cards would have to number \(\frac{2}{5} \times 16 = 6.4\).
What we do and why: you cannot hold 6.4 cards. So with 16 cards the chance of black can never be \(\frac{2}{5}\). That is a sure "no," and a sure "no" answers the question. Statement (1) alone is sufficient.

Step 2. Statement (2): 3 green, 7 black, 6 yellow.
What we see: the full count, \(3 + 7 + 6 = 16\) cards, 7 of them black.
What it means: the chance of black is \(\frac{7}{16}\). Since \(\frac{2}{5} = \frac{6.4}{16}\), the two are not equal.
What we do and why: another sure "no." Statement (2) alone is sufficient.

Step 3. Pick the choice.
Each statement alone answers the question, so the answer is the choice for "each alone is sufficient."

The trap: calling statement (1) not sufficient because "we don't know how many are black." The question only asks whether the chance equals \(\frac{2}{5}\), and the total alone already rules that out. People who miss this pick (B).
Faster way: a probability with denominator 5 needs a total that 5 divides. 16 is not a multiple of 5, so the answer to the question is "no" from the total alone.
Takeaway: in yes-or-no Data Sufficiency, a sure "no" counts as sufficient. Check whether the numbers can even be whole before you ask for more data.

Answer: D