Question: What is the cost of 15 pens, 21 pencils and 18 note books?

Statement-I: The cost of 7 pens, 6 pencils and 5 note books is 200.

Statement-II: The cost of 3 pens, 8 pencils and 7 note books is 210.

Question

Question

This question was previously asked in

CDS Elementary Mathematics 3 Sep 2023 Official Paper

if the question can be answered by using one of the statements alone, but cannot be answered using the other statement alone.
if the question can be answered by using either statement alone.
if the question can be answered by using both the statements together, but cannot be answered using either statement alone.
if the question cannot be answered even by using both the statements together.

Answer 1

Given:

Statement 1 The cost of 7 pens, 6pencils, and 5 notebooks is 200

Statement 2 The cost of 3 pens, 8 pencils, and 7 notebooks is 210

Calculation:

Let, the cost of 1 pen, 1 pencil, and 1 notebook be Rs a, Rs b, and Rs c respectively

According to the question,

⇒ 7a + 6b + 5c = 200 ....(i)

⇒ 3a + 8b + 7c = 210 ....(ii)

If we add both equations

⇒ 10a + 14b + 12c = 410 ...(iii)

If we multiply 1.5 in the equation (iii)

⇒ 15a + 21b + 18c = 605

⇒ 15 pen + 21 pencil + 18 notebook = 615

∴ The correct answer is option 3

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