dreams_come_true Posted March 30, 2009 Share Posted March 30, 2009 Hi guys, it feels like ages when i started preparing for the GMAT and today I stand nowhere, you would get to know this by the level of problems I am posted below. However, I have thought that this time when I give the GMAT I really wanna focus on only my weak areas , so here they are some of them ;) I really hope some angel would help me with them. I know the answer to many of them but I dont know the correct reasoning and explanation behind them so if someone can help me with it, it would be great ! Q1. If b a. x > -3 b. x c. x=3 d. x e. x > 3 Q2. A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^4, what was the number in the population 1 hour later ? a. 2(10^4) b. 6(10^4) c. (2^6)(10^4) d. (10^6)(10^4) e. (10^4)^6 Q3. A certain clock marks every hour by striking a no of times equal to the hour, and the time required for a stroke is exactly equal to the time interval between the strokes. At 6:00 the time lapse between the beginning of the first stroke and the end of the last stroke is 22 seconds. At 12:00, how many seconds elapse between the beginning of the first stroke and the end of the last stroke ? a. 72 b. 50 c. 48 d. 46 e. 44 Q4. The addition problem below shows four of the 24 different integers that can be formed by using each of the digits 1,2,3 and 4 exactly once in each integer. What is the sum of these 24 integers ? 1,234 1,243 1,324 .... .... + 4,321 -------- a. 24,000 b. 26,664 c. 40,440 d. 60,000 e. 66,660 Q5. Four hours from now, the population of the a colony of bacteria will reach 1.28x10^6. If the population of the colony doubles every 4 hours, what was the population 12 hours ago ? a. 6.4 x 10^2 b. 8.0 x 10^4 c. 1.6 x 10^5 d. 3.2 x 10^5 e. 8.0 x 10^6 Q6. At a certain pizzeria, 1/8 of the pizzas sold in one week were mushroom and 1/3 of the remaining pizzas sold were pepperoni. If n of the pizzas sold were pepperoni. How many were mushroom ? a. 3/8n b. 3/7n c. 7/16n d. 7/8n e. 3n Q7. If it is true that x > -2 and x a. x > 2 b. x > -7 c. x d. -7 e. None of the above Q.8. A rectangular box is 10 inches wide, 10 inches long and 5 inches high. What is the greatest possible (straight-line) distance, in inches, between any two points on the box ? a. 15 b. 20 c. 25 d. 10 (2)^1/2 e. 10 (3)^1/2 Many Thanks for all your help and support. Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted March 31, 2009 Share Posted March 31, 2009 Q1. If b a. x > -3 b. x c. x=3 d. x e. x > 3 Here, b is less then 2. and, 2x-3b=0; or, 2x=3b, or, x=(3/2)b. from this if b reduces then x will also reduces. as the maximum value of b is less then 2, So the maximum value of x will be less than 3. So, ans is d. Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted March 31, 2009 Share Posted March 31, 2009 Q2. A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^4, what was the number in the population 1 hour later ? a. 2(10^4) b. 6(10^4) c. (2^6)(10^4) d. (10^6)(10^4) e. (10^4)^6 If the number of population initially is x, then, After 10 minute the population is 2x After 20 minute the population is 4x After 30 minute 8x 40 16x 50 32x 60 64x= (2^6)x = (2^6)(10^4) So, Ans is:C Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted March 31, 2009 Share Posted March 31, 2009 Q7. If it is true that x > -2 and x a. x > 2 b. x > -7 c. x d. -7 e. None of the above Q.8. A rectangular box is 10 inches wide, 10 inches long and 5 inches high. What is the greatest possible (straight-line) distance, in inches, between any two points on the box ? a. 15 b. 20 c. 25 d. 10 (2)^1/2 e. 10 (3)^1/2 7. Answer should be =e here, x>-2 and x a. x>2, So x can be any value which greater than 7 b. x > -7 , x can be less than -2 c. x d. -7 e. None of the above 8. Answer is 15 inch. The greatest possible distance is diagonal drawn from one corner to another corner that is =sqrt(10^2+10^2+5^2)=sqrt(225)=15 Quote Link to comment Share on other sites More sharing options...
dreams_come_true Posted March 31, 2009 Author Share Posted March 31, 2009 Hey thanks a ton, but just one small doubt in the last question Q8. you have used a formula which states sqrt(l^2+b^2+h^2) but I was using some other formula which is sqrt(l x b x h) when is this one used then. I believe it is also used for something like this wherein we have to find the longest chord inside the room.etc. Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted March 31, 2009 Share Posted March 31, 2009 Answer3: At 6:00 there is 6 strokes and 5 intervals between six strokes. As time needed for a stroke and the interval is equal so we can say for 6+5=11 stroke it need 22 second that is 2 second per stroke. At 12:00 there is 12 stroke and 11 interval and time needed is =(12+11)*2=46 second Answer4: There is 24 number and 4 digit. So in every column this 4 digit will appear in 6 times. So sum of one column is 4*6+3*6+2*6+1*6=60 So the sum of the 24 number will be 60*1000+60*100+60*10+60 =60,000+6,000+600+60=66660 Answer 5: After 4 hour the population will be 1.28x10^6 Now the population is (1.28x10^6)/2 Before 4 hour (1.28x10^6)/4 8 (1.28x10^6)/8 12 (1.28x10^6)/16 =(128 x 10^4)/16=8.0 x 10^4 So answer is b. Answer 6: If the total pizza is x then (7/8)*(1/3) of x is =n Or, x = 24n/7 So, 1/8 of x = 3n/7 Answer should be 3n/7 Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted March 31, 2009 Share Posted March 31, 2009 Hey thanks a ton, but just one small doubt in the last question Q8. you have used a formula which states sqrt(l^2+b^2+h^2) but I was using some other formula which is sqrt(l x b x h) when is this one used then. I believe it is also used for something like this wherein we have to find the longest chord inside the room.etc. Yah, we use a formula like this that is simply (l x b x h) measure volume (not sqrt) Quote Link to comment Share on other sites More sharing options...
arindambanerji Posted April 1, 2009 Share Posted April 1, 2009 IMO 1. d 2. c 3. d 4. e 5. b 6. b 7. b 8. a Quote Link to comment Share on other sites More sharing options...
Lock Posted April 8, 2009 Share Posted April 8, 2009 Just a comment on answer to the question number 7: Here, you know for sure that x is more than -2 but less than 7. So, let's say x is -1.9. If you look at answer choice B, then you should be able to admit that whatever value x takes within the range between -2 and 7, the statement B will be satisfied. So, the answer should be B. Quote Link to comment Share on other sites More sharing options...
Md. Minuddin Posted April 9, 2009 Share Posted April 9, 2009 Just a comment on answer to the question number 7: Here, you know for sure that x is more than -2 but less than 7. So, let's say x is -1.9. If you look at answer choice B, then you should be able to admit that whatever value x takes within the range between -2 and 7, the statement B will be satisfied. So, the answer should be B. Its look ok. Actually I was confused with word must be. Quote Link to comment Share on other sites More sharing options...
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