Aptitude - Average - Discussion

P + Q = (5050 x 2) = 10100
Q + R = (6250 x 2) = 12500
P + R = (5200 x 2) = 10400

add above three

2(p+q+r)=33000
(p+q+r)=16500

we need 'p' only so

(p+q+r)-(q+r)=16500-12500

so p=4000...

Friends p=4000 and not 2000.please read the question properly!!they have asked WHAT IS THE MONTHLY INCOME OF P AND NOT WHAT IS THE AVERAGE INCOME OF P.it is given "the average (THE KEY WORD IS AVERAGE!!) monthly income of P and Q is 5050" which means [(p+q)/2] = 5050.therefore the monthly income of p+q = 10100.
similarly the average income of q+r is 6250 which means [(q+r)/2]=6250.therefore the monthly income of q+r = 12500
and in the same manner,the average income of p+r is 5200 which means [(p+r)/2]=5200.therefore the monthly income of p+r is 10400.Now add p+q=10100 and p+r = 10400.therefore the answer is p+q+p+r=10100+10400=20500.So we get 2p+q+r=20500.now minus this with THE MONTHLY INCOME q+r=12500.The result is [(2p+q+r)-(q+r)]=[(20500)-(12500)]=8000.
so 2p=8000 (SINCE Q AND R GET CANCELLED)
P=4000

It's not p=4000 it's p=2000
Let me explain
p+q=5050
q+r=6250
p+r=5200
Therefore we can write -
2(p+q+r)= 16500
p+q+r=16500/2
= 8250
p=8250-(q+r)
But we know that
q+r=6250
p=8250-6250
=2000
Hence p=2000
I hope everyone understand it.