B So far the zoo has sold 4 × 48 = 192 tickets. To make a profit, the zoo will need to sell at
least 350 – 192 = 158 additional tickets. So, z needs to be at least 158. Calculate z in each
of the answers to see which gives you a value of z ≥ 158. In (A), z ≤ 350 – 4(48), so z ≤
Eliminate (A). Choice (B) gives you z ≥ 158. Keep (B). Choice (C) gives you z ≥ –
Eliminate (C). Choice (D) gives you z ≤ –158. Eliminate (D). Choice (B) is the
correct answer.
D Line 1 shows exponential growth, because the line curves upward. Because birth rate and
death rate are per 1,000 people, a birth rate higher than a death rate will result in
exponential growth (because births—deaths will increase as the population increases).
Immigration and emigration numbers are per year and therefore have a linear effect on the
graph (as the absolute change in the population due to immigration—emigration is
constant). South Zealand has more births per 1,000 than deaths per 1,000, so (D) accurately
reflects Line 1.
A Start with Process of Elimination. Since the number of people in the theater decreases over
time, eliminate (D). Choices (A) and (B) are exponential functions, while (C) is linear. The
number of people that leave the theater every 15 minutes is not constant, since it is
proportional to the number of people currently in the theater; therefore, this function is not
linear, and you can eliminate (C). Choice (A) must be correct because the function
decreases quickly and then the number leaving every successive 15 minutes is less than the
time before (10% of 250 is more than 10% of 225).
B Cross-multiply to get 2y^2 = 72. Solve for y to get y^2 = 36, so y ± 6. Another way to solve
would be to Plug In the Answers, since the question asks for a specific value and there arenumbers in the answer choices. In (A), y = –6. Plug –6 into the equation and see if it works:, or . Because this statement is true, one of the possible solutionsfor the equation is y = –6. Eliminate (C) and (D) because neither of these answers includes–6. According to (B), another possible value for y is 6. Plug 6 into the equation to see if itworks: , or . Since this statement is also true, the correct answer is (B).
C The 36-year-old runner ran under 3:00:00 when almost 3:30:00 is expected. The 39-year-
old runner ran slightly above 3:00:00 when 3:30:00 is expected. The 41-year-old runner
ran slightly above 3:00:00 when about 3:45:00 was expected. Therefore, three runners ran
at least 15 minutes faster than predicted, which matches (C). If you chose (B), you may have
based your choice on the number of runners who ran more than 15 minutes slower than their
predicted time.
C According to the table, the relative investment in wind resources in 2007 was 0.40 of the