plz give the answer

If n is a positive integer, is the value of b – a at least twice the value of 3n – 2n?
(1) a = 2n + 1 and b = 3n+1
(2) n = 3


From 1
b-a = (3n+1) - (2n+1) = n
Hence 1 is sufficient

Statement 2 is not sufficient because we do not know the values of a and b

Hence Ans A


Any decimal that has only a finite number of nonzero digits is a terminating decimal. For example, 24, 0.82, and 5.096 are three terminating decimals. If r and s are positive integers and the ratio r/s is expressed as a decimal, is r/s a terminating decimal?
(1) 90 < r < 100
(2) s = 4

Statement 1 is not sufficient as the values of r and s can vary
Statement 2 is sufficient because when a number is divided by 4 , we will end up with a terminating decimal.
Ian has posted about terminating and non-terminating decimanls. An excellent post. Will post that link if I get it.

Ans B

is the value of b – a at least twice the value of 3n – 2n? is quivalent to
is (b-a) - 2*(3n-2n) non-negative? Sometimes rewording helps