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Bunuel
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John bought grocery products for 10 dollars using 55 coins. If John us 10 Sep 2019, 23:17
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25% (medium)

Question Stats:

79% (02:06) correct 21% (01:52) wrong based on 24 sessions

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John bought grocery products for 10 dollars using 55 coins. If John used quarters and dimes, what is the difference between the numbers of dimes to the number of quarters that he used? (quarter = 25 cents, dime = 10 cents)

A. 5.
B. 10.
C. 15.
D. 25.
E. 30.
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John bought grocery products for 10 dollars using 55 coins. If John us 10 Sep 2019, 23:33
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Is the answer to the above question A) 5?

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John bought grocery products for 10 dollars using 55 coins. If John us 10 Sep 2019, 23:35
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Assuming John has used q quarters and (55-q) dimes:
25*q+10(55-q)=10*100 (1Dollar=100 cents)
solving the eq for q: 15q=450 => q=30, so dimes used=55-q=25
so difference between quarters and dimes used = 30-25 = 5 (A)
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John bought grocery products for 10 dollars using 55 coins. If John us 10 Sep 2019, 23:41
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John bought grocery products for 10 dollars( or 1000 cents) using 55 coins.
John used quarters(q) and dime(Dd), where quarter = 25 cents and dime = 10 cents. For the total coins to be 55, John must have used 1 quarter and 3 dimes (only combination possible).

q+3d=55 and 25x+30d=1000 so d-3d=? (difference between # of dimes and quarters used) ----> turned the question into algebraic form.

Multiplying (q+3d=55) x 10 = 10q+30d=550

25x+30d=1000
-(10q+30d=550)
x=30.......(1)

If x=30, 30+3d=55 =>3d=25....(2)

Therefore, d-3d = 30-25 = 5.................OPTION A
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