Stats - GMATPrep Test 1

kwah wrote:I have attached a word doc of a question from GMATPrep Test.

Answer: C

I narrowed it down as follows...

I: yes
II: no
III: at first glance it seems as though the answer is "no". Is there a faster way to conclude the average salary is above $40,000 without calculating the average using each years salary?

Help is greatly appreciated.
K

I. The Klein family's annual income more than doubled from 1985 to 1995.
In 1985, their annual income was $25,000 and in 1995, their annual income was $63,000 approx, which is more than double their annual income in 1985. So, this statement is true.

II. The Klein family's annual income increased by a greater amount from 1985 to 1990 than from 1990 to 1995.
In 1985, their annual income was $25,000.
In 1990, their annual income was $39,000 approx.
In 1995, their annual income was $63,000 approx.
Now, increase from 1985 to 1990 is $39,000 - $25,000 = $14,000 approx
Increase from 1990 to 1995 is $63,000 - $39,000 = $24,000 approx
This means annual income increased by a lesser amount from 1985 to 1990 than from 1990 to 1995. So, this statement is not true.

III. The Klein family's average annual income for the period shown was greater than $40,000.
Average annual income = (25 + 26 + 26 + 35 + 36 + 39 + 39 + 57 + 63 + 63 + 63),000/11 = 472,000/11, which is definitely greater than $40,000.
So, this statement holds true.

The correct answer is C.