Do more than 50 percent of the children in a certain group have brown hair?

(1) 70 percent of the boys in the group have brown hair.
(2) 30 percent of the children in the group are girls with brown hair.

Is n divisible by 12 ?

(1) ~$\frac{n}{6}$~ is an integer.
(2) ~$\frac{n}{4}$~ is an integer.

Each of the offices in a certain building has a floor area of 200, 300, or 350 square feet. How many offices are on the first floor of the building?

(1) There is a total of 9,500 square feet of office floor space on the first floor of the building.
(2) Ten of the offices on the first floor have floor areas of 350 square feet each.

How much time did it take a certain car to travel 400 kilometers?

(1) The car traveled the first 200 kilometers in 2.5 hours.
(2) If the car's average speed had been 20 kilometers per hour greater than it was, it would have traveled the 400 kilometers in 1 hour less time than it did.

Is x > 0 ?

(1) xy > 0
(2) x + y > 0

At a certain bakery, each roll costs r cents and each doughnut costs d cents. If Alfredo bought rolls and doughnuts at the bakery, how many cents did he pay for each roll?

(1) Alfredo paid $5.00 for 8 rolls and 6 doughnuts.
(2) Alfredo would have paid $10.00 if he had bought 16 rolls and 12 doughnuts.

If x and y are positive integers such that x = 8y + 12, what is the greatest common divisor of x and y ?

(1) x = 12u, where u is an integer.
(2) y = 12z, where z is an integer.

If n is an integer between 2 and 100 and if n is also the square of an integer, what is the value of n ?

(1) n is even.
(2) The cube root of n is an integer.

If n is an integer, is -3xⁿ positive?

(1) x is negative.

(2) n is odd.

Is |x| = y - z ?

(1) x + y = z
(2) x < 0