Sentence Correction

Hi, I am having a little trouble in such short sentences. If possible, along with the answers plz give the rule that I can apply. Tq!

1. In the 1980s, the rate of increase of the minority population of the United States was nearly twice as fast as the 1970s.

A. twice as fast as
B. twice as fast as it was in
C. twice what it was in
D. two times faster than that of
E. two times greater than

2. Employment costs rose 2.8 percent in the 12 months that ended in September, slightly less than they did in the year that ended in the previous quarter.
A. less than they did
B. less than it did
C. less than they were
D. lower than
E. lower than they were

varun7nurav wrote:Hi, I am having a little trouble in such short sentences. If possible, along with the answers plz give the rule that I can apply. Tq!

1. In the 1980s, the rate of increase of the minority population of the United States was nearly twice as fast as the 1970s.

A. twice as fast as what - incomplete
B. twice as fast as it was in
C. twice what it was in
D. two times faster than that of
E. two times greater than

Mixed with C and B, will go for B!

2. Employment costs rose 2.8 percent in the 12 months that ended in September, slightly less than they did in the year that ended in the previous quarter.
A. less than they did - they refers to cost; did refers to the rise!
B. less than it did
C. less than they were
D. lower than
E. lower than they were

IMO:A

Great questions here - thanks for posting!

In #1, note that the major problem in the original sentence is that it's comparing "the rate of increase" with "the 1970s". The same is true of E - it's an illogical comparison. We need to compare the rate as it was in the 1980s with the rate as it was in the 1970s - we need to compare like items, rate to rate.

D is also illogical. "That of the 1970s" makes it sound as though the 1970s possessed or owned that rate, when really it's a rate that just occurred in the 1970s. "That of" implies possession, but a decade doesn't possess rates...it's just when the rates occurred.

B and C get more subtle, but it's a logical meaning / logical comparison issue at hand. The rate isn't fast - rate is a measure of speed, not the speed itself. The rate is higher, not faster, just like your height can be high, but not tall. So B is incorrect, whereas C avoids that comparison by avoiding an adjective altogether. C is correct.

@ Brian: Agree with C.

Also, are there any explicit rules about such usage?
When do we use 'more' instead of the '-er' forms of adjectives?