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