How did you do that, I really don't see where the -10, 13 and 15 came from unless im being really stupid :|

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- Jul 17th 2010, 07:09 AMramdrop
How did you do that, I really don't see where the -10, 13 and 15 came from unless im being really stupid :|

- Jul 17th 2010, 09:45 AMundefined
- Jul 17th 2010, 11:14 PMramdrop
Oh right okay, well I solved it to have:

$\displaystyle -4 \le x \le 7$

Seeing as -4 is impossible the smallest value must be 0 and the maxium, 7 - Jul 17th 2010, 11:32 PMundefined
You seem to have kept the loosest bounds and discarded the strictest.

$\displaystyle \displaystyle x \ge 0$

$\displaystyle 7-x \ge 0 \implies x \le 7$

$\displaystyle 6-x \ge 0 \implies x \le 6$

$\displaystyle 4+x \ge 0 \implies x \ge -4$

Discarding the second and fourth, I get $\displaystyle 0 \le x \le 6$ .

IMPORTANT: x is not the value you seek to find the min and max of. You want to find min and max of "the number of male patients under 50 without a back problem" which is 7-x. So...