5 POWER PREP DS Questions... explination needed..

[givinggmat]

Below are five DS questions from Power Prep... Pls provide me with the Approach/Explination on how to crack them.

I do have the answers but shall provide them as soon as i see a correct response. Shall provde you guys with another set as soon as we are done with this.
Thank you all..shall be waiting for responses.

1.During a sale, a clothing store sold each short at a price of $15 and each sweater at a price of $25. Did the store sell more sweaters than shorts during the sale?
a.The avg(am) of the prices of all the shorts and sweaters that the store sold during the sale was $21
b.The total of the process of all the shorts and sweaters that the store sold during the sale was $420

2.If it took carlos ½ hr to cycle form his house to the lib yesterday, was the distance that he cycled greater than 6 miles? 1 mile = 5280 feet
a.The avg speed at which carlos cycled from his house to the lib yesterday was greater than 16 feet/sec
b.The avg speed at which carlos cycled from his house to the lib yesterday was less that than 18 feet/sec

3.Is m+z > 0?
a.M-3z > 0
b.4z-m>0

4.A manufacturer conducted a survey to determine how many Earthlings buy products P and Q. What fraction of the people surveyed said that they buy neither prod P nor prod Q?
a.1/3 of the Earthlings surveyed said that they buy product p but not prod q
b.½ of the Earthlings surveyed said that they buy product Q

5.Martha bought an armchair and a coffee table at an auction and sold both items at her store. Her gross profit from the purchase and sale of the armchair was what % greater than her gross profit from the purchase and sale of the coffee table.
a.Martha paid 10% more for the armchair than for the coffee table
b.Martha sold the armchair for 20% more than she sold the coffee table.

[sonikamadala]

(1) : IMO answer is A
(2) : IMO answer is E
(3) : IMO answer is C
(4) : IMO answer is C
(5) : IMO answer is E

[givinggmat]

Originally Posted by sonikamadala

(1) : IMO answer is A
(2) : IMO answer is E
(3) : IMO answer is C
(4) : IMO answer is C
(5) : IMO answer is E

U got them buddy... explination/approach woudl really really help a ton...

Especially for the following ->

- 2 (the only was i see is multiplying 1/2 hr(1800 sec) with 16.1 and 17.9 which is time consuming..!

- 3 and

- 4

[madboy]

Tried the first three. Will try the last 2 later or may be others can give them a try

1. Let the number of shorts sold be x and that of sweaters be y.
So, total sale price of shorts and sweaters = 15x + 25y
We need to determine if x<y?
Statement a can be framed into the equation -> (15x+25y)/(x+y) = 21 => 4y - 6x = 0 => y/x = 3/2 which is a ratio implying y>x. Thus statement a alone is sufficient (If I am to save time, I wouldn't be simplifying beyond the 2nd step since by this step it becomes pretty clear that I can arrive at the ratio between x and y which is enough to determine if x<y)
From statement b we can write 15x + 25y = 420. Now, remember that both x and y are positive integers.Given this constraint there are only 2 possible values of x and y which satisfy this equation. Clearly these are x=8 and y=12 Thus statement b alone is also sufficient. (This infact is the catch behind most difficult DS problems. They know most candidates upon seeing a single 2-variable equation tend to assume that it cannot be solved. However, that is not the case, if certain conditions are specified and those conditions lead to only one solution to the equation)
The correct answer choice therfore is D

2.Let the avg speed at which Carlos cycled be x ft/sec. So, the distance he cycled = (30 mins) X (x ft/sec) = 1800x feet = d(say) = (1800/5280)x miles = (15/44)x miles
According to statement a, x>16 . Therefore, d > (15/44)16 => d>5.5. From this it is not possible to say if d>6.
Thus, statement a alone is not sufficient

According to statement b, x>18. Therefore, d < (15/44)18 => d<6.1. From this also it is not possible to say if d>6
Combining a and b we get 5.5<d<6.1. Thus, d can have values which are both less than and greater than 6. So both statements taken together are also not sufficient.

The correct answer choice therfore is E


3.Took a stab at this one, but not very sure about the solution.
Statement a : M-3z > 0. Let's quickly think of a pair of values for m and z that will satisfy this inequality as well as m + z>0. How about 4 and 1? Satisfies both. Now let's think of another pair of values which satisfies M-3z>0 but not m+z>0. If we look at both the inequalities carefully, a suitably chosen -ve value for z can serve the purpose. How about m=4 and z=-6? Satisfies m-3z>0 but does not satisfy m+z>0. Thus from these 2 examples, it is clear that statement a is not sufficient to answer the question.
Statement b: 4z - m>0 Applying the same method as above, we can see that even statement b alone is not sufficient
Combining statements a and b, we can write 4z>m>3z => 4z>3z. This is possible only if z is positive and in that case m also has to be positive. Therefore m + z>0
Thus both statements taken together are sufficient. The correct answer choice should be C.

[madboy]

I see many people chosing A for the first 1. However, I think it should be D, what's the OA and is there anything wrong with my explanation?

[sonikamadala]

Originally Posted by givinggmat

U got them buddy... explination/approach woudl really really help a ton...

Especially for the following ->

- 2 (the only was i see is multiplying 1/2 hr(1800 sec) with 16.1 and 17.9 which is time consuming..!

- 3 and

- 4

First question :
(1) : say no.of shirts = x, no.of sweaters = y
cost of a shirt = a=15 and cost of a sweater = b=25.

as per (1)... 15x+25y = 21(x+y)
=> y= 1.5x. It means y>x. So suff

(2) : 15x+25y = 420. so insuff

A wins.

Second question :
question is asking us to find whether distance d is > 6*5280 = 31680 or not.
(1) : say speed s = 17, then distance d = 17*60*30 = 30600 . And 30600 < 31680
if speed s = 17.99, then distance d will be > 31680 . so insuff

(2) : say speed s = 17, then distance d = 17*60*30 = 30600 . And 30600 < 31680
if speed s = 17.99 , then distance d will be > 31680. so insuff

(1)&(2) : say speed s = 17, then distance d = 17*60*30 = 30600 . And 30600 < 31680
if speed s = 17.99 , then distance d will be > 31680. so insuff

E wins

Third question :
(1) : if z = -1 and m = -2, then m+z < 0.
If z and m are =ve ints then m+z > 0. So insuff.

(2) : if z = -1 and m = -5, then m+z < 0.
If z and m are =ve ints then m+z > 0. So insuff.

(1)&(2) : 3z<m<4z. From this z value should be +ve. If z is +ve, then m should be +ve.
Then m+z > 0. So suff.

C wins.

Fourth Question :

say total no.of Earthlings serveyed = E
(1) : only P = E/3. Insuff
(2) : only Q+ P interset Q = E/2. So insuff

(1)&(2) : fraction of the people who buy neither prod P nor prod Q = [E - P Union Q]/E
P Union Q = only P+only Q+ P interset Q. So suff.

C wins

FifthQuestion :
say purchase price of armchair = a
purchase price of coffee table = b
selling price of armchair = x
selling price of coffee table= y

question asking us to find the value for %age p = x-a-y-b/y-b

(1) : a= 1.1b. insuff
(2) : x= 1.2y. insuff
(1) &(2) : not suff.
So E wins

[mahendra rox]

Originally Posted by madboy

I see many people chosing A for the first 1. However, I think it should be D, what's the OA and is there anything wrong with my explanation?

Hey Mad,

For the irst question you have taken x & Y values 8 & 12 respectively. So you got the answer D as correct.But if you try X & Y values 18 & 6 respectively then you will end up with answer A.

[madboy]

Yes, 18 and 6 are also possible. A is correct for # 1

Thanks, mahendra