PRACTICE TEST 3
Answers and Explanations
PRACTICE TEST 3
1 . D
The amount in the account at the end of the x years must be at least 3($400) = $1,200. At the
end of x years, the amount in the account is ($400)(1.07x). You must find the smallest
possible value of x such that ($400)(1.07x) ≥ $1,200. Thus, 400(1.07x) ≥ 1,200. Solve this
equation using natural logarithms.
Using the calculator,
So x ≥ 16.23757....
Since x must be an integer, 16 years will not be enough time for the initial amount invested
to triple. You must have x ≥ 17. The smallest possible value of x is 17.
2 . B
The sum of vectors and is equal to (−3, 7) + (4, −5) = (−3 + 4, 7 + (−5)) = (1, 2).
Then