Aptitude - Average - Discussion

Discussion Forum : Average - General Questions (Q.No. 7)
7.
The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is Rs. 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is:
3500
4000
4050
5000
Answer: Option
Explanation:

Let P, Q and R represent their respective monthly incomes. Then, we have:

P + Q = (5050 x 2) = 10100 .... (i)

Q + R = (6250 x 2) = 12500 .... (ii)

P + R = (5200 x 2) = 10400 .... (iii)

Adding (i), (ii) and (iii), we get:  2(P + Q + R) = 33000  or   P + Q + R = 16500 .... (iv)

Subtracting (ii) from (iv), we get P = 4000.

P's monthly income = Rs. 4000.

Discussion:
93 comments Page 9 of 10.

Sanket jadhav said:   6 years ago
(P+Q)/2 =5050.

P+Q=10100 -----> 1

Similarly;
Q+R=12500 -----> 2
P+R=10400 -----> 3
.
.
.
Addition of these 3 equation.

P+Q+Q+R+P+R = 10100 + 12500 + 10400.
2(P+Q+R) = 33000,
P+Q+R=16500 -----> 4.

Put eqn 2 in eqn 4.

P+12500 = 16500,
P = 16500-12500,
P = 4000.

Sanket bobde said:   6 years ago
Great experience and thank you all for explaining.

Swapnil Andhale said:   6 years ago
Avg = sum/Number.

sum = avg*Number.

ie P+Q = 5050*2.
(2 is a no.of employees, candidate, etc . only P & Q is there ie. multiply it by 2).

Vamsi said:   6 years ago
P&Q+P&R=5050+5200=10250.

Q&R=10250 (PQR total value) -6250 (QR) =4000 this is answer.
(4)

Anjaneyulu said:   5 years ago
In question, he said an average of p and q =5050
Average means the sum of items by a number of items.

Here items are p and q so they are 2 .so the average is p+q/2=5050, dr4 p+q=1100.
(2)

Lokesh patil said:   5 years ago
In simple words, 5050 + 5200 = 10250.

10250 - 6250 = 4000.
(17)

Chandu said:   4 years ago
SIMPLE;

(p+q)/2 = 5050 ------> (1)
(q+r)/2 = 6250 ------> (2)
(p+r)/2 = 5200 ------> (3)
(2) - (1) ------> r= p + 2400.
Substitude r in (3)
(p + p + 2400)/2 = 5020.
2p = 10400 - 2400.
2p =8000.
p = 4000.
(3)

Riz said:   4 years ago
p+q = 10100.
q+r = 12500.
p+r = 10400.

So we can say (p+q)+(q+r)+(p+r) = 10100 + 12500 + 10400.
we can write this as 2(p+q+R)= 33000,
p+q+r = 16500.

Now q+r= we know (12500),
p+12500= 16500,
p= 16500-12500,
Hence p= 4000.
(9)

Selva said:   4 years ago
No confusion we can do like this,

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

We need only p so,

p+q-(q+r)+p+r = p+q-q-r+p+r= 2P(cancel r and q).

10100 - 12500 + 10400 = 8000.
2P = 8000.
P = 4000.
That's it.
(3)

Selva said:   4 years ago
No confusion we can do like this,

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

We need only p so,

p+q-(q+r)+p+r = p+q-q-r+p+r= 2P(cancel r and q).

10100 - 12500 + 10400 = 8000.
2P = 8000.
P = 4000.
That's it.
(6)


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