One morning, each member of Manjul's family drank an \(8\)- ounce mixture of coffee and milk. The amounts of coffee and milk varied from cup to cup, but were never zero. Manjul drank \(\frac{1}{7}\) -th of the total amount of milk and \(\frac{2}{17}\) -th of the total amount of coffee. How many members are there in Manjul's family?
This note is part of the set Pre-RMO 2014
Easy Math Editor
This discussion board is a place to discuss our Daily Challenges and the math and science related to those challenges. Explanations are more than just a solution — they should explain the steps and thinking strategies that you used to obtain the solution. Comments should further the discussion of math and science.
When posting on Brilliant:
*italics*
or_italics_
**bold**
or__bold__
paragraph 1
paragraph 2
[example link](https://brilliant.org)
> This is a quote
\(
...\)
or\[
...\]
to ensure proper formatting.2 \times 3
2^{34}
a_{i-1}
\frac{2}{3}
\sqrt{2}
\sum_{i=1}^3
\sin \theta
\boxed{123}
Comments
Let the total number of members be k, total amount of milk =x ounce, and total amount of coffee =y ounce.
We know that 7x+172y=8
Therefore, 17x+14y=8×7×17
Also, x+y=8k
So, 3x+(14×8)k=8×7×17
3x=56(17−2k)
7x=38(17−2k)
It is given 0<7x<8
0<38(17−2k)<8
0<17−2k<3
0>k−217>−23
217>k>7
7<k<8.5
The only integral value of k satisfying this is k=8
Therefore, there are 8 members in Manjul's family.
Log in to reply
did the same thing..
Approx 8 members
Log in to reply
We can't say apprx 8 members as that might mean there are 7.99 or 8.01 members.
exactly. there are apprx.5 members in my family cuz whyever not? there can be 4.8 members or even 5.3 members. Dude we are like counting members, and however dumb may maths questions get (who buys 300 watermelons, just so that kids have to calculate the total cost?) it will never make us count members in fractions. -Son of Uday Prakash (btw)