SDCAR2010【逻辑入门】（八）Assumptions

PhoebeQi

For question No.2
2. A researcher discovered that people who have low levels of immune-system activity tend to score much lower on tests of mental health than do people with normal or high immune-system activity. The researcher concluded from this experiment that the immune system protects against mental illness as well as against physical disease.
The researcher's conclusion depends on which of the following assumptions?
(A) High immune-system activity protects against mental illness better than normal immune system activity does.
(B) Mental illness is similar to physical disease in its effects on body systems.
(C) People with high immune-system activity cannot develop mental illness.
(D) Mental illness does not cause people's immune system activity to decrease.
(E) Psychological treatment of mental illness is not as effective as is medical treatment.

But if you negate C. people with high immune-system activity CAN develop mental illness. If that is true, then the conclusion that the immune system protects against mental illness is wrong. So why choose D but not c?

-- by 会员 glendasc (2011/7/15 23:25:01)

If you negate C), the conclusion still holds since the conclusion is "the immune system PROTECTs against mental illness,", which means people with high immune system have some protection but that protection is not bullet-proof. So people with high immune system could become mentally unstable, but less likely than those who have low immune system.

-- by 会员 sdcar2010 (2011/7/16 0:02:26)

So what if we negateA)High immune-system activity Does NOT protect against mental illness better than normal immune system activity does.
if this is the case, "the immune system protects against mental illness as well as against physical disease" must be wrong, right? we can conclude immune system does not protect against MI

PhoebeQi

oh I got it!!

PhoebeQi

In the years following an eight-cent increase in the federal tax on a pack of cigarettes, sales of cigarettes fell ten percent. In contrast, in the year prior to the tax increase, sales had fallen one percent. The volume of cigarette sales is therefore strongly related to the after-tax price of a pack of cigarettes.

The argument above requires which of the following assumptions?

A)During the year following the tax increase, the pretax price of a pack of cigarettes did not increase by as much as it had during the year prior to the tax increase.
B)The one percent fall in cigarette sales in the year prior to tax increases was due to a smaller tax increase.
C)The pretax price of a pack of cigarettes gradually decreased throughout the year before and the year after the tax increase.
D)For the year following the tax increase, the pretax price of a pack of cigarettes was not eight or more cents lower than it had been the previous year.
E)As the after-tax price of a pack of cigarettes rises, the pretax price also rises.

I have no idea about it. I choose B. Thx for your help!

PhoebeQi

thank u sooooo much！