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Troubling Questions

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Troubling Questions

by supreetb » Sun Jul 31, 2011 2:00 pm
Hi,

Here are a few troubling questions that i got wrong on my GMAT Prep test . Wonder if you guys can help me in understanding these :

Table :

Months # of days worked

June ---------20
July ---------17
August -------19

1) The table above shows the number of days worked by a sales rep in 3 months last year. If the number of sales calls that the rep made in each month was proportional to the number of days worked in that month and if the rep made a total of 168 sales calls in those 3 months, how many calls did he make in August ?

A)50
B)51
C)56
D)57
E)60

OA : D

2) If xy+z=x(y+z), which of the following must be true?

A)x=0 and z=0
B)x=1 and y=1
C)y=1 and z=0
D)x=1 or y=0
E)x=1 or z=0

OA : E

3) If x is +ve, what is the LCM of x,6,9?

a)LCM of x and 6 is 30
b)LCM of x and 9 is 45

OA : D


Thanks in advance
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by edge » Sun Jul 31, 2011 2:24 pm
1. Let x be the average number of calls made per day. This is constant as per the question. x = 168/(20+17+19) = 3. Hence, number of calls made in Aug = 19 x 3 = 57 (D).

2. Simplifying the given equation, we get z = xz. Therefore, x = 1 or z = 0 (E). Question: why can't it be 'and'? I think Option 'E' should be x = 1 and/or z = 0.

3.
St1 tells us that x = {5, 15, 30}
St2 tells us that x = {5, 15, 45}

Combining, x = {5, 15}
LCM(5, 6, 9) = 90
LCM(15, 6, 9) = 90

Therefore, both statements taken together are sufficient to answer the question. Therefore, D.
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by supreetb » Sun Jul 31, 2011 2:39 pm
Thanks edge!

Your approach to the first question was really good..!! i don't know why could't i think of it :( :(

Anyways.. About the 3rd question, as per your explanation, the answer should be C, which was originally my answer, but the OA id D. Am i missing something here?
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by edge » Sun Jul 31, 2011 2:49 pm
supreetb wrote:Thanks edge!

Your approach to the first question was really good..!! i don't know why could't i think of it :( :(

Anyways.. About the 3rd question, as per your explanation, the answer should be C, which was originally my answer, but the OA id D. Am i missing something here?
I am sorry; as you pointed out, my answer is C and not D. I hope I don't make such mistakes on the GMAT. I think I'll stick with my answer (C); hopefully others can corroborate.
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by MBA.Aspirant » Sun Jul 31, 2011 3:10 pm
Months # of days worked

June ---------20
July ---------17
August -------19

1) The table above shows the number of days worked by a sales rep in 3 months last year. If the number of sales calls that the rep made in each month was proportional to the number of days worked in that month and if the rep made a total of 168 sales calls in those 3 months, how many calls did he make in August ?

A)50
B)51
C)56
D)57
E)60



"the number of sales calls that the rep made in each month was proportional to the number of days worked in that month"

so the ratio of sales calls each month is the same as the number of days worked


20:17:19 sum of ratio = 56
..:..: x total = 168

19:56
x: 168

168 is 3 times 56, so x = 19 * 3 = 57
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by naveen451 » Mon Aug 01, 2011 1:02 am
for second question

IMO A
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by naveen451 » Mon Aug 01, 2011 1:14 am
edge wrote:
supreetb wrote:Thanks edge!

Your approach to the first question was really good..!! i don't know why could't i think of it :( :(

Anyways.. About the 3rd question, as per your explanation, the answer should be C, which was originally my answer, but the OA id D. Am i missing something here?
I am sorry; as you pointed out, my answer is C and not D. I hope I don't make such mistakes on the GMAT. I think I'll stick with my answer (C); hopefully others can corroborate.
FOR THIRD QUESTION

IN OPTION A,

x can be 5 or 30,both will give lcm 30

lcm of 5,6,9 or 30,6,9. will give the same lcm 90

IN OPTION B,

X can be 5 or 45,both will give lcm 45

lcm of 5,6,9 or 45,6,9 will give the same lcm 90


so answer is D
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