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08 Jun 2016, 05:06
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
74% (02:51) correct
26%
(02:35)
wrong
based on 156
sessions
History
Date
Time
Result
Not Attempted Yet
Ashley paid 5 dollars for 1 notebook and 1 pencil. If both prices were integers, how many pencils did Ashley buy if she paid 93 dollars for the pencils and for 15 notebooks?
A. 6.
B. 16.
C. 18.
D. 21.
E. 26.
A. 6.
B. 16.
C. 18.
D. 21.
E. 26.
08 Jun 2016, 05:37
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Bunuel
let the price of notebook be N and that of pencil be P..
so P+N=5........so 15P+15N = 75.......(i)... so both P and N should be less than 5
also xP+ 15N = 93.....(ii)
subtract (i) from (ii).....
xP + 15N - 15P - 15N = 93-75 .............................(x-15)P=18 ......
Now both x and P are integers.... and P is less than 5, so value of P that are also factor of 18 are 1,2,3......
If P = 1, x-15 = 18/P = 18 or x=33....
If P = 2, x-15 = 18/2 = 9 or x = 24...
If P=3, x-15 = 18/3 = 6 or x=21...
So she could have purchased 21 or 24 or 33..
21 is in choices
D 21
08 Jun 2016, 07:00
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I solved this question in a slightly different way:
5 = 1P + 1 N
93 = XP + 15N, where X is the number of pencils
Possible prices for 1P & 1N (integers):
N = 1 P = 4 then 15N = 15, 4X = 93 - 15 = 78, X = 19.5 (not an integer)
N = 2 P = 3 then 15N = 30, 3X = 93 - 30 = 63, X = 21 (the answer we were looking for, no need to continue calculations)
N = 3 P = 2
N = 4 P =1
Answer: D
5 = 1P + 1 N
93 = XP + 15N, where X is the number of pencils
Possible prices for 1P & 1N (integers):
N = 1 P = 4 then 15N = 15, 4X = 93 - 15 = 78, X = 19.5 (not an integer)
N = 2 P = 3 then 15N = 30, 3X = 93 - 30 = 63, X = 21 (the answer we were looking for, no need to continue calculations)
N = 3 P = 2
N = 4 P =1
Answer: D
