Prep 7. Section 1. Question 16 Forum

[eternallearner]

Why is (B) the right answer. Given that it is the best answer in the selection, their answer choice still contradicted my quick sample calculation.

Assume that in 1990, we thought the comet reflected 100%. However, in 2000, we discovered that the comet actually reflected only 60% (as dictated by the question stem). Since mass is proportional to the amount reflected, we can conclude that in 1990, we overestimated the mass and the reflected power of the comet. Thus, why is (B) the right answer?

Thank you so much!

[lebob]

hm, i remember this problem from memory, hopefully this will help



yes mass is proportional to the amount reflected. however, they discovered that the amount reflected PER UNIT OF MASS is less than they initially expected. the "per unit of mass" part is key. so, you have the same amount of light shining in 1990 and 2000, but since its discovered that each unit of mass reflects less light, you need more mass to account for the same amount of light in 2000.


numerical example: let's say in 1990, the dude saw 1000 units of light from the comet.
in 1990, he believed that each kilogram (of mass) of the comet reflected 100 units of light. that means that he estimated the mass of the comet to be 10 kilograms (1000/100 = 10)

in 2000, he discovers that he overestimated the amount of light that each kilogram of the comet reflects. he discovers that each kilogram reflects, say, only 10 units of light. the original 1000 units of light have to be divided by the smaller number, 10. that equals 100 kilograms (which is larger)


well, uhhhh, i hope i didnt confuse you more. i just gave you a numerical example, let me come back a bit later and see if i can clarify that a bit more

[eternallearner]

Thank you for your reply. Let me ask you another question on the same Prep7.

It is Prep 7. Section 4. Question 20.
Why can't (C) be the right choice? In a way, I see why (A) is the right choice (though I do not agree with the word "absurd" which I think is an extreme language.)

Another question. Prep 7. Section 4. Question19.
How were you able to conclude that (B) was the right choice? Every 7th day (using Jan 1 a Sunday) would be a Saturday, which is a free day already. Where is the conflict?

Thank you!

[lebob]

i looked at choice (c), and i think i need to see your reasoning.
(c) is wrong because there is nothing in the stimulus that talks about people being analyzed, and those people knowing beforehand what/how they are being analyzed (and thus actively trying to change their behavior to cover for it). what part did you read to interpret it like that?

(a) is correct because it uses seemingly incontestable evidence ("obviously, with practice people can alter their handwriting"), that leads to absurd consequences ("permanent traits can be changed") (afterall, permanent = cannot be changed), when conjoined with the view in question ("it is possible to detect permanent character traits by examining people's handwriting")

[eternallearner]

"when the people analyzed..." I assumed that since we are inspecting a person's handwriting in the hopes to learn about their personality, they are being analyzed.

[lebob]

let me personal message you and try to help you out