Saturday GMAT quizzing - quant

As promised, I am posting some GMAT questions here for practice. The answers will be posted tomorrow.

1. Machine A can produce 50 components a day while machine B only 40. The monthly maintenance cost for machine A is $1500 while that for machine B is $550. If each component generates an income of $10 what is the least number of days per month that the plant has to work to justify the usage of machine A instead of machine B?
A. 6
B. 7
C. 9
D. 10
E. 11

2. There are positive integers P, Q, and R. Are they all equal?
(1) P = Q
(2) Q^2 = R^2
(x^y denotes x raised to the power of y)

3. There are four distinct pairs of brothers and sisters. In how many ways can a 3 person committee be selected so as NOT to have siblings in it?
A. 24
B. 32
C. 48
D. 60
E. 80

4. In how many ways can the letters of the word ARRANGE be rearranged so that neither the two R nor the two A come together?
A. 5040
B. 1260
C. 830
D. 660
E. 540

5. What is the remainder when the +ve integer n is divided by the positive integer k, where k>1?
1) n=(k+1)^3
2) k=5

6. A straight picket fence is composed of x pickets each of which is ½ inches wide. If there are 6 inches of space between each pair of pickets, which of the following represents the length of the fence in feet?
A. 13x/2
B. 13x/2 - 6
C. 13x/24
D. { 13x + 1 }/24
E. {13x – 12}/24

7. What is the smallest possible common multiple of two integers which are both greater than 250?
A. 251
B. 252
C. 502
D. 750
E. 884

8. If the market value of a car was $6000 exactly 3 years ago, what is its current market value?
1) Since the time of purchase, the market value of the car depreciated by 20% of its purchase price per year.
2) The current market value of a car manufactured in the same year is $2400

9. Does p^2 = q if p is a prime number?
1) q^2 – p^2 = 0
2) p^2 = 49

10. The probability of pulling a black ball out of a glass jar is 1/X. The probability of pulling a black ball out of a glass jar and breaking the jar is 1/Y. What is the probability of breaking the jar?

A. 1/(XY)
B. X/Y.
C. Y/X.
D. 1/(X+Y)
E. 1/(X-Y)