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New Set of Mixed Questions!!!
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01 Apr 2013, 07:48
The next set of medium/hard PS questions. I'll post OA's with detailed explanations on Friday. Please, post your solutions along with the answers.1. The distance from the Yaxis to point K is 1/3 of the distance from the Xaxis to point K. If the coordinates of K are (3, y), what is the distance between point K and Xaxis?A. 1/2 B. 1 C. 3 D. 4.5 E. 9. Solution: https://gmatclub.com/forum/newsetofm ... l#p12084362. What is the area of a region enclosed by x/3+y/9=10?A. 675 B. 1350 C. 2700 D. 5400 E. 10800 Solution: https://gmatclub.com/forum/newsetofm ... l#p12084413. Three workers, A, B, and C, can complete a certain task in 10, 5 and x hours respectively. A starts working alone and 2 hours later B joins. After another 2 hours joins C. After that A, B, and C together complete the task in 15 minutes. What is the value of x?A. 1 B. 1.25 C. 2 D. 2.5 E. 4 Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084454. A draining pipe can empty a pool in 4 hours. On a rainy day, when the pool is full, the draining pipe is opened and the pool is emptied in 6 hours. If rain inflow into the pool is 3 liters per hour, what is the capacity of the pool?A. 9 liters B. 18 liters C. 27 liters D. 36 liters E. 45 iters Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084495. For a certain set of numbers, if x is in the set, then both x^2 and x^3 are also in the set. If the number 1/2 is in the set , which of the following must also be in the set ? I. 1/64 II. 1/64 III. 1/2^(1/3) A. I only, B. II only, C. III only, D. I and II only E. I, II and III Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084546. A team contributes total of $399 from its members. If each member contributed at least $10, and no one contributed $19, what is the greatest number of members the club could have?A. 37 B. 38 C. 39 D. 40 E. 41 Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084577. Mary spent 64 percent of her salary on food (including meat) and 16% of her salary on meat. What percent of the salary spent on food were not spent on meat? A. 16% B. 25% C. 32% D. 48% E. 75% Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084598. Usually Holly leaves home to school at 9:00, however today she left home 20 minutes later. In order to be at school on time she increased her usual speed by 20% and still was at school 15 minutes later than usual. What is her usual time from home to school?A. 15 minutes B. 20 minutes C. 25 minutes D. 30 minutes E. 210 minutes Solution: http://gmatclub.com/forum/newsetofmi ... l#p12084629. If x and y are integers and x + y = 12, which of the following must be true?A. Both x and y are negative B. xy > 0 C. If y < 0, then x > 0 D. If y > 0, then x < 0 E. x  y > 0 Solution: http://gmatclub.com/forum/newsetofmi ... l#p120846610. If n is a nonnegative integer and the remainder when 3^n is divided by 4 is a multiple of 3, then which of the following must be true?I. n^2 divided by 4 yields the reminder of 1 II. (2)^n is less than 0 III. n is a prime number A. I only B. II only C. III only D. I and II only E. II and III only Solution: http://gmatclub.com/forum/newsetofmi ... l#p1208471BONUS QUESTION: 11. Certain bowl contains 5 red marbles and 3 blue marbles only. One by one, every marble is drawn at random and without replacement. What is the probability that the seventh marble drawn is NOT blue?A. 7/8 B. 3/4 C. 2/3 D. 5/8 E. 3/8 Solution: http://gmatclub.com/forum/newsetofmi ... l#p1208473Kudos points for each correct solution!!!
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Re: New Set of Mixed Questions!!!
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05 Apr 2013, 06:07
11. Certain bowl contains 5 red marbles and 3 blue marbles only. One by one, every marble is drawn at random and without replacement. What is the probability that the seventh marble drawn is NOT blue?A. 7/8 B. 3/4 C. 2/3 D. 5/8 E. 3/8 Basically we need to find the probability that the seventh marble drawn is red (so not blue). Now, the initial probability of drawing red marble is 5/8. Without knowing the other results, the probability of drawing red marble will not change for ANY successive draw: second, third, fourth, ..., seventh. Thus the probability that the seventh marble is red is 5/8. The same for blue marble: the probability of drawing blue marble is 3/8, the probability that for instance the 8th marble drawn is blue is still 3/8. There is simply no reason to believe WHY is any draw different from another (provided we don't know the other results). Answer: D.
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Re: New Set of Mixed Questions!!!
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01 Jan 2014, 11:40
11. Certain bowl contains 5 red marbles and 3 blue marbles only. One by one, every marble is drawn at random and without replacement. What is the probability that the seventh marble drawn is NOT blue?
A. 7/8 B. 3/4 C. 2/3 D. 5/8 E. 3/8
answer:
We fix the seventh ball to be red. Since all balls are same it doesnt matter which of the red balls.
So the rest 7 balls can be arranged in 7!/(4!*3!)= 35 ways becoz there are 4 identical red balls and 3 identical blue balls.
Without any restriction 8 balls can be arranged in 8!/(5!*3!) = 56 ways.
Therefore probability is 35/56 = 5/8.




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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:02
1. The distance from the Yaxis to point K is 1/3 of the distance from the Xaxis to point K. If the coordinates of K are (3, y), what is the distance between point K and Xaxis?
Point k is on the line x=3, so its distance form the yaxis (x=0) is 3. Given that "The distance from the Yaxis to point K is 1/3 of the distance from the Xaxis", its distance to the yaxis is 3*3=9
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:08
2. What is the area of a region enclosed by x/3+y/9=10?
We can analize the function x/3 + y/9 = 10 first. y=903x This intersect the Yaxis is 90 and the Xaxis in 30. The original function ( with the absolute values) has the same graph as y=903x, only symmetric for value of x<0 and values of y <0. So the answer is: it defines a triangle of Area=\(\frac{90*30}{2}=1350\)
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:14
3. Three workers, A, B, and C, can complete a certain task in 10, 5 and x hours respectively. A starts working alone and 2 hours later B joins. After another 2 hours joins C. After that A, B, and C together complete the task in 15 minutes. What is the value of x? rates : A=1/10 B=1/5 c=1/x
A*2h+(A+B)*2h+(A+B+C)*15min = 1 work.
(1/10)*2 +(1/10+1/5)*2+(1/10+1/5+1/x)*1/4=1
x=2 IMO C



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:20
4. A draining pipe can empty a pool in 4 hours. On a rainy day, when the pool is full, the draining pipe is opened and the pool is emptied in 6 hours. If rain inflow into the pool is 3 liters per hour, what is the capacity of the pool?
To empty X liters ==> 4 h. To empty X + 3*6 liters ==> 6 h.
\(\frac{x}{4}=\frac{x+18}{6}\)
\(x=36\)
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:28
5. For a certain set of numbers, if x is in the set, then both x^2 and x^3 are also in the set. If the number 1/2 is in the set , which of the following must also be in the set ?
I. 1/64 II. 1/64 III. 1/2^(1/3)
If 1/2 is in the set, then 1/2^2 and 1/3^3 are in the set. (1/4 and 1/8 are in the set) If 1/4 is in the set, then (1/4)^2 and (1/4)^3 are in the set. (1/4)^3 = 1/64 so II is in the set, IMO B



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:34
6. A team contributes total of $399 from its members. If each member contributed at least $10, and no one contributed $19, what is the greatest number of members the club could have?
To maximize the number of members we have to minimize the number of dollars donated by each one. So we use 10$ donations as long as we can, given the conditions in the question. Number of members who donated 10 dollars = 37. Tot = 370. The remaining 29 dollars are splitted between 2 members ( 15 and 14 for example) Tot members = 37+2=39
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:37
7. Mary spent 64 percent of her salary on food (including meat) and 16% of her salary on meat. What percent of the salary spent on food were not spent on meat?
Salary 100$. 64 dollars on food, 16 dollars on meat and 6416=48 dollars on "nonmeat" $on nonmeat/$on food = 48/64= 0.75
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 08:45
9. If x and y are integers and x + y = 12, which of the following must be true?
A. Both x and y are negative False : 113=12 B. xy > 0 False: 1*(13)<0 C. If y < 0, then x > 0 False: 66=12 D. If y > 0, then x < 0 True E. x  y > 0 False: 13+1=12 and 131<0



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:10
1. The distance from the Yaxis to point K is 1/3 of the distance from the Xaxis to point K. If the coordinates of K are (3, y), what is the distance between point K and Xaxis?
A. 1/2 B. 1 C. 3 D. 4.5 E. 9.
The distance between Y axis and (3,y) will be the distance between (0,y) and (3,y)
which is (3)^2=9



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:13
2. What is the area of a region enclosed by x/3+y/9=10?
A. 675 B. 1350 C. 2700 D. 5400 E. 10800
x/3+y/9=10 will touch the xaxis at (30,0) and yaxis at (0,90) in Q1. Area of this region will be .5*30*90=1350. Hence the total area of the figure formed on all the 4 quadrants is 4*1350=5400



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:13
8. Usually Holly leaves home to school at 9:00, however today she left home 20 minutes later. In order to be at school on time she increased her usual speed by 20% and still was at school 15 minutes later than usual. What is her usual time from home to school?
s=t*v She left 20 minuters later ==>you subtract 20 minutes for her time; but arrived 15 min later ==>you add 15 to her time She increase the speed by 20% ==> you multiply her speed by 6/5 = 1.2 And finally since she walked the same distance you equal her "normal" equation : space=time*speed, to her new equation so : \((t20+15)*\frac{6}{5}v=t*v\) divide by v \((t5)6/5=t\) \(t=30\)
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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:21
3. Three workers, A, B, and C, can complete a certain task in 10, 5 and x hours respectively. A starts working alone and 2 hours later B joins. After another 2 hours joins C. After that A, B, and C together complete the task in 15 minutes. What is the value of x?
A. 1 B. 1.25 C. 2 D. 2.5 E. 4
Work done by : A in 2 hrs = 2/10.(1) A and B in 2 hrs = 2(1/10 + 1/5)(2) A,B and C in 15 mins = 1/4(1/10 + 1/5 + 1/x)(3) (1)+(2)+(3) =1
on simplification 4/5 + 1/4(3/10 + 1/x) = 1
or 1/x= 4/5 3/10 = 5/10 = 1/2
X= 2 hrs



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:24
4. A draining pipe can empty a pool in 4 hours. On a rainy day, when the pool is full, the draining pipe is opened and the pool is emptied in 6 hours. If rain inflow into the pool is 3 liters per hour, what is the capacity of the pool?
A. 9 liters B. 18 liters C. 27 liters D. 36 liters E. 45 iters
I have actually back solved this question. Took 36 liters as capacity of the tank. Hence draining pipe rate is 36/4 = 9 l/hr.
now total out flow during rain is 93= 6 l/hr. multiply with 6 hrs  time taken to empty the tank we arrive back at the original capapcity of the tank = 36 L



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:27
5. For a certain set of numbers, if x is in the set, then both x^2 and x^3 are also in the set. If the number 1/2 is in the set , which of the following must also be in the set ?
I. 1/64 II. 1/64 III. 1/2^(1/3)
A. I only, B. II only, C. II only, D. I and II only E. I, II and III
My answer is D.
Since 1/2 is there we have 1/4 and 1/8 in the set. Since 1/4 is there we will have (1/4)^3= 1/64. 1/8 is there hence (1/8)^2 = 1/64 will be in the set.



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:30
6. A team contributes total of $399 from its members. If each member contributed at least $10, and no one contributed $19, what is the greatest number of members the club could have?
A. 37 B. 38 C. 39 D. 40 E. 41
37 ppl each contributing 10$ = total 370 $. remaining 29$ can be split between 2 people ( 14 + 15 or any other combination meeting the criteria.
Hence total 39 members



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:32
7. Mary spent 64 percent of her salary on food (including meat) and 16% of her salary on meat. What percent of the salary spent on food were not spent on meat?
A. 16% B. 25% C. 32% D. 48% E. 75%
let Mary's total salary = 100. Sal spent on food = 64(1), sal spent on meat = 16. food exp not spent on meat = 6416=48.(2) 2 as a % of 1 is 48/64 = 75%



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Re: New Set of Mixed Questions!!!
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01 Apr 2013, 09:40
8. Usually Holly leaves home to school at 9:00, however today she left home 20 minutes later. In order to be at school on time she increased her usual speed by 20% and still was at school 15 minutes later than usual. What is her usual time from home to school?
A. 15 minutes B. 20 minutes C. 25 minutes D. 30 minutes E. 210 minutes
D= dist of school. V= actual speed.
D/v= T time taken to reach school.
when she was 20 mins, time taken would be T+20
when she increased her speed to 6/5 ofher original. time taken is T+15.
now the difference of 5 mins in the time is due to 20% increase in speed.
d/v  (d/1.2v) = 5
1/6*(d/v) = 5
D/V= T= 30 mins




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