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Eleanor is making chocolate chip cookies for her friends. If she divides the cookies equally among 11 of her friends, she'll have 4 cookies left over. If she divides the cookies equally among 7 of her friends, she'll have 1 cookie left over. Assuming that Eleanor made fewer than 100 cookies, what is the sum of the possible numbers of cookies that she could have made?

 

...The only number I could find was 15, but 15 isn't the correct answer. Please help!

 Sep 3, 2016
 #1
avatar+37091 
0

15?   59 ?  92?

 

Added together equals 166

 Sep 3, 2016
edited by ElectricPavlov  Sep 3, 2016
edited by ElectricPavlov  Sep 3, 2016
 #2
avatar+129840 
0

Let N be the number of cookies

 

And we have that

 

N =  11m + 4

N =  7n + 1       subtracting the second equation form the first, we have

 

11m - 7n = -3   →  11m  = 7n - 3

 

And the  only possible values for {m,n}  are  {1, 2}  or (8, 13}

 

Thus N  could be either 15 or 92

 

And their sum = 106

 

 

cool cool cool

 Sep 3, 2016
 #3
avatar+37091 
+5

Phil is correct (as usual)   ...I do not know how I came up with 59 while I was on my bike ride doing this in my head this morning.....

HOWEVER    92 + 15  equals    107      NOT 106 as Phil added.

ElectricPavlov  Sep 3, 2016

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