-
joshhowatt
- Junior | Next Rank: 30 Posts
- Posts: 18
- Joined: Mon Mar 19, 2012 12:53 pm
I am beating my head on this one from GMAT Prep. Someone please help.
The cost of a certain phone call was $.75 for the first 3 minutes and $.20 for each additional minute after the first 3 minutes. Did the phone call last longer than 15 minutes?
1.) The cost of the call was less than $4.16
2.) The cost of the call was greater than $3.35
Looks easy enough, right?
The OA is: C
Although upon working through it I came up with E
My logic:
subtract .75 from 4.16 you get 3.41. Then I can divide 3.41 by .20 to give me the number of LESS THAN minutes. m<17 INSUF
Same for 2. subtract .75 from 3.35 gives 2.6$, divide by .20 gives must be GREATER THAN 13 m>13 INSUF
Combining the two gives us options for 14, 15, 16. Which would be insufficient.
However, the explanation that GMAT Prep gives is that we're to use a formula .75 + (.2)(t-3) subbing in minutes for t starting with 15 and working our way up determining a price structure. I'm having a hard time figuring out how my logic doesn't pan out. Can someone please help?
Same for
The cost of a certain phone call was $.75 for the first 3 minutes and $.20 for each additional minute after the first 3 minutes. Did the phone call last longer than 15 minutes?
1.) The cost of the call was less than $4.16
2.) The cost of the call was greater than $3.35
Looks easy enough, right?
The OA is: C
Although upon working through it I came up with E
My logic:
subtract .75 from 4.16 you get 3.41. Then I can divide 3.41 by .20 to give me the number of LESS THAN minutes. m<17 INSUF
Same for 2. subtract .75 from 3.35 gives 2.6$, divide by .20 gives must be GREATER THAN 13 m>13 INSUF
Combining the two gives us options for 14, 15, 16. Which would be insufficient.
However, the explanation that GMAT Prep gives is that we're to use a formula .75 + (.2)(t-3) subbing in minutes for t starting with 15 and working our way up determining a price structure. I'm having a hard time figuring out how my logic doesn't pan out. Can someone please help?
Same for
