AAPL wrote:Manhattan Prep
Phone plan A charges $1.25 for the first minute and $0.15 for every minute thereafter. Phone plan B charges a $0.90 connection fee and $0.20 per minute. Which of the following equations could be used to find the length, in minutes, of a phone call that costs the same under either plan?
A. 1.25 + 0.15x = 0.90x + 0.20
B. 1.25 + 0.15x = 0.90 + 0.20x
C. 1.25 + 0.15(x – 1) = 0.90 + 0.20x
D. 1.25 + 0.15(x – 1) = 0.90 + 0.20(x – 1)
E. 1.25 + 0.15x + 0.90x + 0.20 = x
OA C
Phone plan A charges $1.25 for the first minute and $0.15 for every minute thereafter.
Let x = total duration of phone call (in minutes)
So, the cost of an x-minute call =
$1.25 + ($0.15)(x - 1)
ASIDE: I created the expression ($0.15)(x - 1) because we pay $1.25 for the FIRST minute. So, if x = the TOTAL call time, then x-1 = the time spent AFTER the first minute)
Phone plan B charges a $0.90 connection fee and $0.20 per minute.
Let x = total duration of phone call (in minutes)
So, the cost of an x-minute call =
$0.90 + ($0.20)(x)
Which of the following equations could be used to find the length, in minutes, of a phone call that costs the same under either plan?
We need:
$1.25 + ($0.15)(x - 1) =
$0.90 + ($0.20)(x)
Answer: C
Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
