Question 2:

Let X = the number of employees that retire

(560 - X) / (800 - X) = .60

560 - X = 480 - .6X

80 = .4X

200 = X

Question 5
Statement 1 - 5 /\ 6 = 6 /\ 5
So it is either multiplication or addition
(5 x 6) x 2 = 60
5 x (6 x 2) = 60

(5 + 6) + 2 = 13
5 + (6 + 2) = 13

So this is sufficient.

2 /\ 0 = 2

So it is either addition or subtraction

(5 + 6) + 2 = 13
5 + (6 + 2) = 13

(5 – 6) – 2 = -3
5 – (6 – 2) = 1

So we are not sure whether the 2 statements from the question are equal and this is insufficient.

Answer is A

Question 1
There is only one pair of the expressions that yield the form of x^2-(by)^2 ; (x+y) and (x-y)
So let find p(u) that is 4C2 = 6

Therefore the answer is 1/6

Question 5
From 1 possible operations are + and *. Therefore , reclassification under these symbols always yields the same outcome.
From 2 possible operations are + and -. Since (5-6)-2 is not equal to 5-(6-2) , therefore , 2 is not sufficient.

For your 4th Question,

x and y are not integers. so x and y can even be positive or negative numbers.

In both (1) and (2) information about x and y are given in terms of x+y and x-y. Note that x and y can take any number of values to satisfy both (1) and (2).

(1) and (2), either individually or taken together, is insufficient.

Hence (E).

Question 3

statement 2 is sufficient

imo B

first lets examine statement 1

Sun 1
Mon - 2
Tue - 3
Wed - 6
Thurs 8
Fri - 10
Sat - 60

60+10+8+6+3+2+1 = 90

or

Sun 1
Mon - 2
Tue - 3
Wed - 4
Thurs 8
Fri - 12
Sat - 60

1+2+3+4+8+12+60 = 90

Hence, above results prove that books sold on friday could be greater than 11 or less than 11. Therefore, statement 1 is insufficient.

Now, moving on to statement 2

Sun - 5
Mon - 6
Tue - 7
Wed - 8
Thurs 9
Fri - 11 (Has to be the second highest)
Sat - 38 (has to be the highest)

5+6+7+8+9+11+38 = 45+38 = 84 (this is the maximum number of books which could be sold if books sold on friday are 11 (or not greater than 11)

So, statement 2 proves that books sold on friday HAVE to be greater than 11.

imo B

For your question 3:

As per the statement, Store S sold different number of copies on ANY TWO OF THE DAYS, and also states that Store S sold greatest number of copies on Satrurday and second greatest number on Friday,

so its a clue only on Friday and Saturday, Store S sold different number of copies and rest all 5 days sold the same number of copies.

1. 8 books on thursday

Insufficient: Gives the number of copies sold from Mon - Thu, but what about Friday/Saturday?

2. Sold 38 books on Saturday

Sufficient:

Satrurday: 38

Remaining copies: 52,
As store S sold same number of copies from Mon-Thu, try any number 2,3,4,5,6,7,8 all of these number suggests Store S sold more that 11 copies on Friday.

Hence Answer B.