grandh01 wrote:Kim bought a total of $2.65 worth of
postage stamps in four denominations.
If she bought an equal number of
5-cent and 25-cent stamps and twice
as many 10-cent stamps as 5-cent
stamps, what is the least number of
1-cent stamps she could have bought ?
(A) 5
(B) 10
(C) 15
(D) 20
(E) 25
To MINIMIZE the number of 1-cent stamps, we must MAXIMIZE the number of the other types of stamps.
She bought an equal number of 5-cent and 25-cent stamps.
She bought twice as many 10-cent stamps as 5-cent stamps.
In other words, for every 5-cent stamp, one 25-cent stamp and two 10-cent stamps must be bought:
5+25+2(10) = 50.
Thus, the sum of the other types of stamps must be a multiple of 50.
The greatest multiple of 50 less than 265 is 250.
Since 265-250 = 15, 15 cents must be spent on 1-cent stamps.
Thus, the number of 1-cent stamps = 15.
The correct answer is
C.
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