Some DS and PS, Please Help

[bretania]

Guys, these are not tough questions for many of you here. But somehow I just can see the light on these ones. Any help is appreciated.

Thanks in advnace!

#1 DS. (please explain.. OA will follow)
Is XY > 0?

1. X-Y > -2
2. X-2Y < -6

#2 PS
(for this problem, i solve it a number of times but my answer doesn't match the OA. The source of the problem is reliable. So there must be something I'm missing)
A was walking at a constant rate of 4 miles per hour. B is on bicycle travelling in the same direction along the smae path at constant rate of 20miles/hour.

B stops to wait for A 5 mins after passing A, while the A continues to walk at her constant rate. How many mins. must B wait until A catches up?

#3 DS
In 1995, Division A of company X had 4,850 customers. If there were 86 service errors in Div A that year, what was the service-error rate, in number of service errors per 100 customers, for Division B of company X in 1995?

1. In 1995, the overall service-error rate for Div A and B combined was 1.5 service errors per 100 customers.

2. In 1995, Div B had 9,350 customers, none of whom were customers of Div. A.

#4. DS again (have you guys noticed.. there are just way more DS now than PS). For this problem, somehow I could imagine why the answer is such. But I need input as to how to approach this kind of problem.

In a certain year, the UN's total expenditures were 1.6B dollars. Of this amount, 67.8% was paid by 6 highest countries, and the balance was paid by the remaining 153 countries. Was country X among the 6-highest contributing countries?

1. 56% of the total expenditures was paid by the 4 highest-congtributing countires each of which paid more than country X.

2. Country X paid 4.8% of the total expenditures.

[clock60]

for 1
i think answer is C
y>4, x>2

[clock60]

q2
in 5 minutes bicycle travel 5/60*20=5/3 km
in 5 minutes A will travel 5/60*4=1/3 km
distance between them 5/3-1/3=4/3
(4/3)/4=1/3 or 20 min

[clock60]

q3
i think C
let it be x=number of errors in B
y=number of customers in B we must find x/y-?
(1) (86+x)/(4850+y)=1.5
here one equation and two unknows so insuff
(2) y=9350 insuff
(1)+(2) insert y in first eq with two unknowns so we can solve the equation
for x and y
my answer C

[bretania]

clock 60, thanks again.
i'm still reading your solution.
AND yes, you're right. the OA for #1 is C, and for #3 is also C.
For #2, I think you're right but let me just double check the OA.

Please try #4 too.

[bretania]

Clock, thanks! you're great!
u got everything correct.

now, am waiting for num 4.

[sonikamadala]

for 1 IMo is C.
For 2 IMO is 20 min.
For 3 IMO is C.
For 4 IMO is E

Q4 :

(1) : say countries a,b,c,d made total of 56%. Say countries e and f made reamining 11.8%.
(Total of 67.3 %) . So X need not to be the one of the highest 6 countries. SO insuff

(2) : say countries a,b,c,d made 10%,10%,10%,16%. And e and f made 5.5% and 6.3%. All are > 4.8%. (Total of 67.3 %) . So X need not to be the one of the highest 6 countries. SO insuff

(1)& (2) : say countries a,b,c,d made 10%,10%,10%,16%. And e and f made 5.5% and 6.3%. All are > 4.8%. (Total of 67.3 %) . So X need not to be the one of the highest 6 countries. SO insuff

E wins

[CyberSpy]

yep answer for 4 is E

amount paid by 6 high paying cntries is 1.08 b - (1)

frm 2 amt paid by cntry x is .0768 - (2)

frm 1 amt paid by hihst 4 cntris is .896 - (3)

(1)-(3)= .184

2 possiblties are there for the remng 2 high paying countries.

both can be greater than (2) or only one of them can be greater than (2)