Answer

Solution

UPSC Prelims

Mathematics

Theme:

Statistics / सांख्यिकी

Q45 2022, Statistics

Five friends P, Q, X, Y and Z purchased some notebooks. The relevant information is given below:
1. Z purchased 8 notebooks more than X did.
2. P and Q together purchased 21 notebooks.
3. Q purchased 5 notebooks less than P did.
4. X and Y together purchased 28 notebooks.
5. P purchased 5 notebooks more than X did.
If each notebook is priced 40, then what is the total cost of all the notebooks?

पाँच मित्र P, Q, X, Y और Z ने कुछ नोटबुक खरीदीं। संगत सूचनाएँ नीचे दी गई हैं:
1. X ने जितनी नोटबुक खरीदीं उससे 8 अधिक नोटबुक Z ने खरीदीं।
2. P और Q ने मिलकर 21 नोटबुक खरीदीं।
3. Q ने P ने जितनी नोटबुक खरीदीं उससे 5 कम नोटबुक खरीदीं।
4. X और Y ने मिलकर 28 नोटबुक खरीदीं।
5. P ने X ने जितनी नोटबुक खरीदीं उससे 5 अधिक नोटबुक खरीदीं।
यदि प्रत्येक नोटबुक की कीमत 40 है, तो सभी नोटबुक की कुल लागत कितनी है?

Explanation Please wait..

As per question

1. Z = X + 8,

2. P + Q = 21,

3. Q = P – 5,

4. X + Y = 28,

5. P = X + 5.

Solving 2 and 3 we get P = 13, Q = 8 (numbers of books purchased)

Putting value of P in 5 we get X = 8

This way we also find value of Y and Z from other equations as 20 and 16 respectively.

So total number of books (P + Q + X + Y + Z) = 21 + 28 + 16 = 65.

Each book cost 40, total cost = 65 × 40 = 2600.

व्याख्या Please wait..

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