Cracking The SAT Premium

Since   it  is  given   in  the question    that    a   >   0   when    the parabola    is  in  the form    y   =   ax^2    +   bx  +   c,

the parabola    must    be  pointed upwards—eliminate   (D) and choose  (B).

28. A Since the radius of the circle is 4, the area of the entire circle is πr^2 = π(4^2 ) = 16π. Sector

POR has an  area    of  8π  and sector  ROQ has an  area    of  6π, so  the remaining   sector  (QOP)

has an  area    of  16π –   8π  –   6π  =   2π. You can set up  a   proportion  to  determine   the associated

angle   using   the following   formula:     .  Using   the numbers you now

have,   your    calculation will    look    like    this:       or   .  Multiply

both    sides   of  the equation    by  360 to  determine   that    the sector  angle   is  45°,    which   is  (A).

29. D 16% of the 200 medical residents named oncology as their first choice: (200) or

(0.16)(200) =   32  residents.  40% of  the 200 medical residents   named   cardiology  as  their

first   choice:     (200)   or  (0.4)(200)  =   80  residents.  Of  these   80  residents,  20% chose

oncology    as  their   second  choice:  (80)   or  (0.2)(80)   =   16  residents.  The total   number  of

residents   who named   oncology    as  either  their   first   or  second  choice  was therefore   32  +   16

=   48  residents.  To  find    the value   of  x,  you need    to  subtract    the percentages given   in  the

question    from    the total,  100%:   100 –   40  –   16  –   34  =   x   =   10%.    Now,    plug    x   =   10  into    the

answer  choices in  order   to  determine   which   one matches your    target  of  48  residents.  Only

(D) works:  x^2     –   24x +   188 =   100 –   24(10)  +   188 =   100 –   240 +   188 =   48.

30. 
    

    B If the original graph is reflected across the x-axis, the x-values will remain the same but the
    y-values will switch signs. Since the y-axis represents distance from start, negative y-
    values means that the car is now going in reverse. The only answer that matches this
    information is (B).

    
    


31. 
    

    30 Translate English to math. “What number divided by two is equal to that same number

    
    

minus   15?”    can be  written as  an  equation,   with    x   representing    the missing number:     =   x   −

15. Add 15 to both sides of the equation to get + 15 = x. Subtract from both sides to get

15  =    .  Multiply    both    sides   by  2   to  get x   =   30.