GRE Math Problem 39

x>90

Column A	Column B
The length of AB	7

Solution for GRE Math Problem 38:
How many three-digit numbers are?
The first digit can be any of 9, the second - any of 10, so does the third. Total 9x10x10=900 combinations.

How many three-digit palindromes are?
The first digit can be any of 9, the second - any of 10, and the third one must be exactly the same as the first, thus, leaving only 1 possibility. Total 9x10x1=90.

The probability that a three-digit number chosen at random is a palindrome is 90x900=0.1
Answer: C

GRE Math Problem 21

The figure below consists of four circles with the same center. The radii of the four circles are 1, 2, 3, and 4.
Compare two values:

Column A	Column B
The area of the shaded region	The area of the yellow region

Solution for GRE Math Problem 20:
Since x + y = a, y + z = b, and x + z = c, a+b+c=2x+2y+2z=2(x+y+z). So, x+y+z=. And the average of x, y and x is
Answer:(D)