CXD page 51 question 35

Excluding purchases by business, the average amount spent on a factory-new car has

risen 30 percent in the last five years. In the average household budget, the proportion

spent on car purchases has remained unchanged in that period. Therefore the average

household budget must have increased by 30 percent over the last five years.

(A) The average number of factory-new cars purchased per household has remained

over the last five years.

(B) The average amount spent per car by business buying factory-new cars has risen

30 percent in the last five years.

(C) The proportion of the average household budget spent on all car-related expenses

remained unchanged over the last five years.

(D) The proportion of the average household budget spent on food and housing has

remained unchanged over the last five year.

(E) The total amount spent nationwide on factory-new cars has increased by 30

percent over the last five years.

A is the correct answer.

The explanation from the book is kind of complicate but very effective. If I use the logic provided by the book and follow the steps, I will get to A is the correct answer, but it took me at least 5 minutes. My question is how to approach this kind of question in the first place and solve it in a much quicker way? Guidance needed please.

57

One sure way you can tell how quickly a new idea, for example, the idea of

“privatization”, is taking hold among the population is to monitor how fast the word

or words expressing that particular idea are passing into common usage. Professional

opinions of whether or not words can indeed be said to have passed into common

usage are available from dictionary editors, who are vitally concerned with this

question.

The method described above for determining how quickly a new idea is taking hold

relies on which one of the following assumptions?

(A) Dictionary editors are not professionally interested in words that are only rarely

used.

(B) Dictionary editors have exact numerical criteria for telling when a word has

passed into common usage.

(C) For a new idea to take hold, dictionary editors have to include the relevant word

or words in their dictionaries.

(D) As a word passes into common usage, its meaning does not undergo any severe

distortions in the process.

(E) Words denoting new ideas tend to be used before the ideas denoted are

understood.

Correct answer is D.

And why B is not correct? Will it make B an Assumption if remove "exact numerical" out of the sentence? Confused here. sign. help please.