Sat practice Test #8 Answer Explanations

Choice C is correct. Based on the line of best fit shown, the predicted 
percent of leaf litter mass remaining for a forest with a mean annual 
temperature of −2°C is about 70%.
Choice A is incorrect; it is the predicted percent of leaf litter mass 
remaining at about 6.5°C. Choice B is incorrect; it is the predicted 
percent of leaf litter mass remaining at 2°C instead of at −2°C. 
Choice D is incorrect; it is the predicted percent of leaf litter mass 
remaining at about −7°C.

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ANSwER ExPlANATIONS
| SAT Practice Test #8
QUESTION 19
Choice A is correct. Since zeros of f correspond to the x-intercepts of 
the graph of f, and the range of f gives all the possible y-values on the 
graph of the function, the correct graph of the function has only points 
with y-values less than or equal to 4, and crosses the x-axis at only
(−3, 0) and (1, 0). The graph in choice A satisfies both of these 
conditions.
Choice B is incorrect. The graph of the function matches the range 
given, but the zeros are at −1 and 3, not −3 and 1. Choice C is incorrect. 
The graph has y-values greater than 4. Choice D is incorrect. Even 
though the graph has zeros at −3 and 1, it has an additional zero at 0, 
and the range of the graph is the set of all real numbers.
QUESTION 20
Choice B is correct. The savings each year from installing the 
geothermal heating system will be the average annual energy cost for 
the home before the geothermal heating system installation minus 
the average annual energy cost after the geothermal heating system 
installation, which is (4,334 − 2,712) dollars. In t years, the savings will 
be (4,334 − 2,712)t dollars. Therefore, the inequality that can be solved 
to find the number of years after installation at which the total amount 
of energy cost savings will exceed (be greater than) the installation 
cost, $25,000, is 25,000 < (4,334 − 2,712)t.
Choice A is incorrect. It gives the number of years after installation 
at which the total amount of energy cost savings will be less than the 
installation cost. Choice C is incorrect and may result from subtracting 
the average annual energy cost for the home from the onetime cost 
of the geothermal heating system installation. To find the predicted 
total savings, the predicted average cost should be subtracted from 
the average annual energy cost before the installation, and the result 
should be multiplied by the number of years, t. Choice D is incorrect 
and may result from misunderstanding the context. The ratio
4,332
_ 
2,712
compares the average energy cost before installation and the average 
energy cost after installation; it does not represent the savings.
QUESTION 21