DS - Set 1 - Can't figure out the answers - 3 questions

[cardoc]

1)If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p > ?
(1) More than of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than .

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

answer- E



Mary persuaded n friends to donate $500 each to her election campaign, and then each of these n friends persuaded n more people to donate $500 each to Mary's campaign. If no one donated more than once and if there were no other donations, what was the value of n?
(1) The first n people donated 1/16 of the total amount donated.
(2) The total amount donated was $120,000.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer - D



In the xy-plane, what is the slope of line l?
(1) Line l dose not intersect the line with equation y = 1 - x.
(2) Line l intersects the line with equation y = x - 1.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer - A

Can't figure out the answers

[cardoc]

Correction !!!!!- First Question should read as


If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p >1/2 ?
(1) More than of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10 .

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

[rijul007]

If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p >1/2 ?
(1) More than of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10 .

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

Please check the red part again.

[rijul007]

Mary persuaded n friends to donate $500 each to her election campaign, and then each of these n friends persuaded n more people to donate $500 each to Mary's campaign. If no one donated more than once and if there were no other donations, what was the value of n?
(1) The first n people donated 1/16 of the total amount donated.
(2) The total amount donated was $120,000.

Given
Total donation collected = $ 500 * n * (n+1)

Ques
What is the value of n

Statement 1
The first n people donated 1/16 of the total amount donated.

500 n(n+1)/16 = 500 n
n+1 = 16
n = 15


Sufficient


Statemet 2
The total amount donated was $120,000.
500 n(n+1) = 120000
n(n+1) = 240
n = 15

Sufficient


Option D

[rijul007]

In the xy-plane, what is the slope of line l?
(1) Line l dose not intersect the line with equation y = 1 - x.
(2) Line l intersects the line with equation y = x - 1.

Statement 1

Line l dose not intersect the line with equation y = 1 - x.
line l is parellel to y = 1-x
both the lines have the same slope (i.e. -1)


Sufficient


Statement 2

Line l intersects the line with equation y = x - 1.

the two lines are not parellel

nothing else is clear from this statement


Insufficient

Option A

[cardoc]

Apologies , first question should read as


If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p >1/2 ?
(1) More than 1/2 of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10 .

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

[rijul007]

If 2 different representatives are to be selected at random from a group of 10 employees and if p is the probability that both representatives selected will be women, is p >1/2 ?
(1) More than 1/2 of the 10 employees are women.
(2) The probability that both representatives selected will be men is less than 1/10 .

Total no of ways of selecting 2 rep (T) = 10C2 = 45

Statement 1
No of women(w) > 5
No of ways of selecting 2 women (W) > 5C2
W > 10
Probability > 10/45

Insufficient

Statement 2
Probability that both are men < 1/10
No of ways of selecting 2 from m men (M) = mC2 = m(m-1)/2
Probability < 1/10
m(m-1)/9*10 <1/10
m(m-1) < 9
m^2-m-9 < 0
solving
m<3.5 or we can take it as
m<4
w > 6
Probabilty > 15/45

Insufficient

Combining the 2 statements

from S1 we get... w>5
from s2 we get... w>6

Both insufficient



Option E