Question

HELP!!!

MA.912.D.6.4

Shelly, Susan, and Samantha are all working at an amusement park for the summer. The manager finds out that one of them left the key in the door to the security office. When he asked them who did it, they replied:

Shelly: Susan did it.
Susan: I didn’t do it.
Samantha: Susan did not do it.

The manager concluded that Susan did it because she was accused and was denying it.

Use an indirect proof to show that the manager was wrong and that Susan did not leave the key in the security office door.

Answer 1

HERES THE REST OF THE POST
Answer
Selected Answer:
' if Susan did not leave the key in the security office door then, the manager is wrong'

Response Feedback:
Assume that Susan did leave the key in the door. Shelly’s statement that Susan did it would then be true/false? Can you finish the proof from here?

Answer 2

what does the teacher wnat me todo differently here?

Answer 3

Lol ... I think i faced this question before.

Answer 4

yes!! lol and i thought we had it right then my teacher gave me part credit and said 'Assume that Susan did leave the key in the door. Shelly’s statement that Susan did it would then be true/false? Can you finish the proof from here?' after i put '' if Susan did not leave the key in the security office door then, the manager is wrong' as an answer and soo now idk what she wants me to do....

Answer 5

I am not sure about these kind of stuff to ... looks like philosophy material than mathematics. let's see what we can do.

Answer 6

yeahh i have no clue how these kinda proofs have anything todo with math. but mmks thanks-ya

Answer 7

Shelly's statement would have been right ... because Susan left the key at the off.

Answer 8

BYW which standard student are you?? I could guess what type of answer it would be.

Answer 9

what do you mean?

Answer 10

In which grade do we usually face these kinds of questions??

Answer 11

9th - geometry

Answer 12

If Shelly was wrong then statement "Susan did it" would have been wrong
== which means => Susan didn't do it.

Manager concluded that Susan did it ^^ but Susan did not do it ^^ which means manager would have been wrong.

Answer 13

so my original answer i still correct then right? why is my teacher saying 'Assume that Susan did leave the key in the door. Shelly’s statement that Susan did it would then be true/false? Can you finish the proof from here?' if thats not what the question is saying

Answer 14

Assume that Susan did leave the key in the door.
Then manger would have been correct
Then Shelly would have been correct.

But shelly is not correct, which means our assumption is incorrect
Susan did not leave the key.

Answer 15

oooh gotcha!!! so on my assighnment do i leave my original answer but add that in as well

Answer 16

well, not really sure ... what you meant by that.

Answer 17

like should i do the comparison about if susan had left the key then both the manager and shelly would also be right but since we know that susan didnt we know shelly isnt right

Answer 18

i guess adding my later statement to the first one might serve as a comparison ...
you see language is not my forte.

Answer 19

haha it's ok i think iv'e got it =) and really? english/language is what comes easiest to me i have As in my other classes then i get to geometry and i have a C.... never been my strong point.

Answer 20

well, proving logic verbally is quite difficult than proving it algebraically.

Answer 21

yeahh well thanks for helping me!!