GMAT PREP

what is the shortest way to solve this

if 0<r<1<s<2, which of the following must be less than 1?

I. r/s
II. rs
III. s-r

a. I only
b. II only
c. III only
d. I and II
e. I and III


the way I solved it is very time consuming

the ans is A

prep test

:

Prep test I

The number 75 can be written as the sum of the squares of 3 different positive integers. What is the sum of these 3 integers?

17
16
15
14
13

GMAT Prep 1

what is the best approach for problems like this one:

if 0<R<1<S<2, which of the following must be less than 1

I. R/S
II. R*S
III. S-R

Prep Test 2

a contest will consist of n questions, each of which is to be answered either "true" of "false". anyone who answers all n questions correctly will be a winner. What is the least value of n for which the probability is less than 1/1000 that a person who randomly guesses the answer...

practice question 55

if (t- 8 ) is a factor of (t^2)- kt-48
then k =


16
12
2
6
14

ans is C

Paper Test

If the sum of the first n positive integers is S, what is the sum of the first n positive even integers, in terms of S

s/2
s
2s
2s+2
4S

ans S

48^5/12^5=4^5
4^5=2^5*2^5=2^10