Elitmus
Exam
Numerical Ability
Number System
Is (p+r)(q+r) odd?
1. p is odd, q is odd.
2. q is odd, r is odd.
Which is correct?
a-1 only
b-2 only
c-Both 1 & 2
d-Neither 1 nor 2
Read Solution (Total 14)
-
- Neither 1 nor 2
- 7 years agoHelpfull: Yes(29) No(4)
- ANS: B
2 only
statement 1: if we assume
CASE1: r is even
(odd[p]+even[r])(odd[q]+even[r])
(odd[p+r])(odd[q+r])
=>odd*odd= odd
CASE 2: r is odd
(odd[p]+odd[r])(odd[q]+odd[r])
=>even*even= even
Statement 2:
odd[q]+odd[r]=even
even*any number (p+r)=even
so, with only statement it can be determined that (p+r)(q+r) is not odd
and is b-2 only - 7 years agoHelpfull: Yes(12) No(6)
- Ans- 1 only
p is odd, q is odd
(odd + even)(odd + even)
(odd)*(odd) = odd
so answer is p is odd, q is odd - 7 years agoHelpfull: Yes(10) No(15)
- st1=> p is odd , q is odd
if r is even then
P(odd)+r(even)=odd
q(odd)+r(even)=odd
result= odd*odd=odd
else
if r is odd then
P(odd)+r(odd)=even
q(odd)+r(odd)=even
result even*even= even
in stmt 1 dosn't give unique answer so stmt one is not ture
in stmt 2
q(odd)+r(odd)=even
so
(P+r) is odd or even doesn't mean the multiplication of two if one is even the result always be even
so answer found no form ans: b-2 - 7 years agoHelpfull: Yes(10) No(17)
- I don't know you guys are thinking from which point of view
But you need Both to ans the question - 7 years agoHelpfull: Yes(3) No(1)
- stmt 1: take p=3(odd),q=5(odd) , first put r=2(even) we get (p+r) (q+r)=5*7=35(odd),
now ,put r=9(odd) we get (p+r) (q+r)=12*14=168(even) so stmt 1 not satisfied condition
stmt 2: take q=3(odd), r=5(odd) first put p=2(even), we get (p+r) (q+r)=7*5=35(odd)
now put p=3(odd) we get (p+r) (q+r)=8*8=64(even) so stmt 2 also not satisfied
ANSWER is: d-Neither 1 nor 2 - 6 years agoHelpfull: Yes(3) No(0)
- Answer is b-2
Sol:
First consider Statement 1: Let us suppose r is odd, then p(odd)+r(odd)--> even.
q(odd)+r(odd)--->even.
Now, let us suppose r is even, then p(odd)+r(even)--->odd.
& q(odd)+r(even)-->odd.
Hence nounique answer if we consider just statement 1.
Similarly evaluate this for statement 2, You will find out that statement 2 gives unique answer.
Hence, answer is b-2. - 7 years agoHelpfull: Yes(2) No(1)
- p is odd and q is odd. then sum of odd and even gives odd number and final result is product of two odd numbers is odd
- 7 years agoHelpfull: Yes(1) No(2)
- statement 1
(odd+even)(odd+even)=odd
(odd+odd)(odd+odd) =even so we can see question is depend upon r we can not tell
statement 2
(even+odd)(odd+odd)
so whatever the value of (p+r) ,(q+r) will be always even so
it is sufficient to tell that NO
its not odd
so ans will be
only statement 2 required to tell
Note - for who dont know the concept of data sufficiency
in question asking is it odd so if so u dont have to proof its odd
u just have to tell yes or no by statement so if yes then its true if its no its allso true
only will be wrong if its ans is ambiguos means when its give yes or no both
u are not sure . - 7 years agoHelpfull: Yes(1) No(1)
- (p+r).(q+r)= odd (acc. to given situation)
RULE:- odd*odd=Odd
Option 1- (3+2).(5+2)= odd
(Let P and Q as an odd no and R as an even no.)
5.7= odd
35= odd
Option 2- (2+5).(7+5)=odd
(Let q and r as an odd no. And P as an even no)
84 is not an odd no
Hence option 1 (1only) satisfy the condition - 6 years agoHelpfull: Yes(1) No(1)
- 2 only
q(odd)+r(odd)=even - 7 years agoHelpfull: Yes(0) No(5)
- 2 only since first have 2 answers with 2 diff types of value of r.But 2nd case
If p=odd & r is odd then then p+r=even
(Anything)×(even)=even
Since this gives answer of our question that given term is not odd. - 7 years agoHelpfull: Yes(0) No(1)
- p-odd, q-odd, r-odd
(odd+odd)(odd+odd)
(even)(even)
even
is (p+r)(q+r) odd ans d-Neither 1 nor 2 - 6 years agoHelpfull: Yes(0) No(0)
- Neither 1 nor 2
- 5 years agoHelpfull: Yes(0) No(0)
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