broall wrote:
Some accountants calculate with simple adding machines, and some use complex computers. One can perform more calculations in less time with a computer than with an adding machine. Therefore, assuming the costs of using the two types of machines are equal, an accountant who uses a computer generally can earn more per hour than an accountant who uses an adding machine.
Which one of the following is an assumption that would make the conclusion in the passage a logical one?
(A) More accountants use computers than use adding machines.
(B) The more hours an accountant spends on the job, the more money he or she will earn.
(C) The more calculations an accountant performs, the more money he or she will earn.
(D) An accountant who uses an adding machine can charge a higher hourly rate than one who uses a computer.
(E) In general, accountants vary in terms of the number of calculations they make and the amount of money they earn.
Source: LSAT
OFFICIAL EXPLANATION
(A) No. The argument is concerned with comparisons between accountants who use adding machines and those who use computers. It is not concerned with comparisons of the relative number of accountants in each group.
(B) No. This does not relate to computers.
(C) Yes. Since the passage states that a computer can perform more calculations is less time than an adding machine (in other words, more calculations per hour) and that an accountant can earn more per hour using a computer, the passage needs to assume that the more calculations an accountant performs, the more money he or she will earn.
(D) No. This contradicts the argument. The argument concludes that “
an accountant who uses a computer generally can earn more per hour than an accountant who uses an adding machine” whereas this answer-choice states the opposite.
(E) No. This is irrelevant. The argument is concerned with two categories of accountants—those who use adding machines and those who use computers.