- Thread starter
- #1

https://www.dropbox.com/s/xjq0i38dz8j6jeh/Photo Nov 16, 1 05 11 PM.jpg

- Thread starter safaulk
- Start date

- Thread starter
- #1

https://www.dropbox.com/s/xjq0i38dz8j6jeh/Photo Nov 16, 1 05 11 PM.jpg

- Jan 30, 2012

- 2,571

I can't help you with using the calculator (perhaps somebody else on this forum can), but I can explain why the answer is 136, as the linked picture says. If you are getting 137, that's pretty close to the correct result. Why are you saying that you are expected to get 78?

For starters, here are the relevant graphs (the picture is clickable).

[GRAPH]00wufkkqgc[/GRAPH]

Please let me know if you need help of this sort.

- Admin
- #3

- Mar 5, 2012

- 9,740

I suspect your daughter is calculating something different from what was intended.

https://www.dropbox.com/s/xjq0i38dz8j6jeh/Photo Nov 16, 1 05 11 PM.jpg

Let me try and explain the reason for the answer 78 and perhaps it will help you two to figure out what whent wrong.

The answer 78 should come out for the bottom right corner of the double shaded region.

This is where the line $Y=8X-48$ has its ZERO ($Y = 0$).

In other words, where $8X-48 = 0$.

The corresponding $X = 6$.

So the bottom right corner is at $X = 6$ and $Y = 0$.

The objective function in the bottom right corner is

$$13X + 2Y = 13 \times 6 + 2 \times 0 = 78$$