Data Sufficiency

sk63818 · Joined: 20 Jun 2004 Posts: 3

1. What is the fourth consecutive even number in a given series of even real numbers?

s1.The sum of first two numbers is 18.
s2.The sum of last two numbers is 26.

choices.

A.if s1 alone is sufficient but s2.alone is not
B.s2 is sufficient but s1 alone is not
C.s1,s2 together sufficient but neither alone is sufficient.
D.if each statement alone is sufficient.
E.s1,s2 together are not sufficient

jerrya · Joined: 21 Oct 2004 Posts: 1

answer: D.if each statement alone is sufficient.

solution
even means has to be a multiple of 2
now let the number be n
so the series will be n,n+1.........& so on..........this is consecutive.

sum of first 2 is 18
therefore
2n + 2(n+1)=18
4n+2=18
n=16/4=4

therefore the first number is 2(4)=8

hence, last no will be 2(n+3) = 2(7)=14

the series 8,10,12,14
8+10=18
12+14=26

hope u got this.

cheers,
jerry

neerajj · Joined: 29 Aug 2005 Posts: 7

The solution to this DI question will be A as statement s1 is sufficient to get the answer but the statement s2 is not sufficient alone as in that cas we dont know the starting even number of the series .

pallavi19 · Joined: 06 Oct 2005 Posts: 2

can anyone tell me how can I improve DS, I am really very poor in it and always lose marks in it Confused

MEENAL SHARMA · Joined: 29 Oct 2005 Posts: 4

hey pallavi,
DS is all game of confidence .... there r just a couple of rules u need to keep in mind and then DS is a child's play ....these rules will take a couple of days to sink in bt ones its in ... u ll have a 90 to 95% of striking rate ... these are:
1. yes and no both are acceptable answers. like ...is a>b? .....if both the options can tell u yes or no .... then either of them are sufficient .... the answers fetched frm the 2 options cn be differnt bt if they answer the question .. they r sufficient
2. a unique solution frm a particular statement is compulsory ... u r nt allowed to have more than 1 answer frm a single statement...
3. no extra assumptions of course
4. u dont have to waste time in getting the rt answer
5. different answers frm different statements are acceptable
6..... very very imp.......READ THE INSTRUCTIONS VERY CAREFULLY....it happens so many times tht in CAT the options are interchanged frm usual. like mark 1 if more info is needed to answer the quetions .... man tis the biggest blunder !!!!!!! i ve done it in a prac cat ....so be careful ... practice ... practice n practice ....

Salar · Joined: 24 Jan 2006 Posts: 6 Location: Chennai

Neeraj,

Either of A or B is sufficient to solve the problem
Assume that the numbers are a-2,a,a+2,a+4. Try out both a and b independently you ll arrive at the amswer

CZ@@@H@@@R · Serious about CAT Joined: 14 Jan 2006 Posts: 64

Series satisfying : Sum of first two = 18 in a given series of even real numbers. The series could be

(2, 16, 30, 44 ------)
(4, 14, 24, 34 ------)
(6, 12, 18, 24 ------)
(8, 10, 12, 14, -----)

Series satisfying : Sum of last two = 26 in a given series of even real numbers. The series could be

( ----, 12, 14)
( ----, 10, 16)

Series satisfying both could be
(8,10,12,14) and is the only series possible and is unique

So both are sufficient but neither alone is sufficient Hence (C)

Please correct it, If required.