G.I. problem from practice test

What we see: a Graphics Interpretation pie chart of votes, in thousands, for six parties: A 2,872, B 2,322, C 806, D 501, E 257 and F 83. We need how many parties got less than 5 percent of all votes.

Step 1. Find the total number of votes.
What we see: six slice labels.
What it means: 5 percent is measured against the total, so we need the total first.
What we do and why: add in easy pairs. \(2872 + 2322 = 5194\), \(806 + 501 = 1307\), \(257 + 83 = 340\). Total: \(5194 + 1307 + 340 = 6841\) thousand votes.

Step 2. Find 5 percent of the total.
What we see: total 6,841.
What we do and why: 10 percent is 684.1, so 5 percent is half of that, about 342. Any party under 342 got less than 5 percent.

Step 3. Compare each small party with 342.
What we see: the four big parties, A, B, C and D, all have 501 or more, so they are above 342. Party E has 257 and Party F has 83.
What it means: only E and F are under 342. Party D, at 501, is about 7.3 percent, so it is safely above the line.
What we do and why: count them: 2 parties.

The trap: "Three parties" comes from using 10 percent (684) by mistake, which also pulls in Party D. "One party" comes from looking only at the thinnest slice, F, and judging the others by eye.
Faster way: round the slices to 2,900, 2,300, 800, 500, 250 and 100. The total is about 6,850, so 5 percent is about 340. Only the two smallest slices are under it.
Takeaway: To check "less than 5 percent", find 10 percent of the total, halve it, and compare each part to that one number.

Answer: Two parties