Q24 - Biologist: We know the following

[weiyichen1986]

Hi,

I am wondering can anyone diagram this one for me,

here is mine: Fuzz seed---->Long stems and no white flower
seedpods---->curled leaves----->white flower

so Long stems and curled leaves--->white flower

but how do we infer no fuzz seeds??

I can only infer the White flower though

[timmydoeslsat]

Look closely at your statements! You can infer ~fuzzy seeds from the contrapositive. We know that fuzzy seeds require ~white flowers, and we do have white flowers in this specimen.

So we know it lacks fuzzy seeds!

[sweetygurl]

1. FS --> LS AND ~ WF
CONTRA: WF OR ~LS --> ~ FS

2. CL --> WF
CONTRA: ~WF --> ~CL

3. TS --> CL
CONTRA: ~CL --> ~TS

we are given
X--> LS AND CL
let's find this in the statements above
(there is no LS as a trigger, so let's focus on CL)

CL --> WF --> ~ FS
VOILA!
If CL--> then we know that it has white flowers BUT does not have fuzzy seeds.

Hope this helps.

if you encounter a lot of FL statements in an inference/must be true question, then it is the best to carefully yet strategically write down every formal logic statement and its contrapositive. (this may be time consuming - but if you use acronyms or symbols and arrows to quickly jot down, it is actually not as time consuming as you may think!)

-K

[WaltGrace1983]

Fuzzy --> Long Stems
Fuzzy --> ~White Flowers

Curled --> White Flowers

push these two things together and we get...

Curled --> White Flowers --> ~Fuzzy

Thorny --> Curled

push these two things together and we get...

Thorny --> Curled --> White Flowers --> ~Fuzzy

Here is the list of all the formal logic, pushed all together:

Thorny --> Curled --> White Flowers --> ~Fuzzy
Curled --> White Flowers --> ~Fuzzy
Fuzzy --> Long Stems

Prompt: Long Stems & Curled


What we know: X must have white flowers and ~fuzzy

(C) fits this.