GMAT Critical reasoning : (2) Strengthen and WEakening

P.140

Q1.

Conclusion: Mountain biking on trail is getting a lot more popular
Evidence: The sale number of mountain bike has increased and the proportion of sales of mountain bike was over 65% of their total sales.
Assumption: people who buy mountain bike must be using them on trail.
Predict strengtheners:
Predict weakeners: people who purchase the mountain bikes tend to ride them in urban or suburban settings with another purpose, rather than on trail. 

Q2.
Conclusion: shoe customers like man-made leather more than natural leather.
Evidence: the man- made leather shoes was sold more than the natural leather shoes.
Assumption: leather is the most important factor for customer to purchase shoes. quality of man-made leather and natural and other conditions are totally same or rather man made higher than natural one..

Predict strengtheners:
Predict weakeners: customer consider the design or price more than quality of leather.


Conclusion: the most homeless people can not work
Evidence: 85%of the homeless are suffering mentally ill.
Assumption: people who suffering mentally ill can not work.


Predict strengtheners:
Predict weakeners:


P.143

Conclusion: He would limit most of what he have done which gave less profit
Evidence: He did success recently and Lawton can be more selective about screening his client.
Assumption: commercial job and pricey residential job have higher profit margin than inexpensive residential works.



P.145


Conclusion: Business should not be prosecuted for flying large garrison flags rather than smaller post flag.
Evidence:  Legal technicalities should not restrict patriot expression
Assumption: the businesses are flying the garrison flag out of a sense of patriot expression, rather than for some other reasons. 


Conclusion:player who use steroid should be limited to competition.
Evidence: steroid benefits user of drug to get greater strength and weight than non-user
Assumption: greater strength and weight provides athletes with a competitive advantage.


Conclusion: airbags would prevent only a small % of serious injuries
Evidence: Use of seat belts would prevent from most accidents inducing serious injuries.
Assumption: most people wear seat belts. 

=> Both the evidence and the conclusion use the phrase "serious injuries" so there's no scope shift there. But in order to be protected by seat belts, a person must wear seat belts. 

Conclusion: Artistic success of actor depends on how well an actor has developed his craft.
Evidence: actor who take many classes appeared the more number of professional production.
Assumption:(1) the number of classes taken is equivalent to how well developed an actor's craft (2) artistic success correlates to the number of productions as actor has appeared in.