Question

the cost of a pack of 20 pencils is rs400 and a pack of 17 eraser is rs199. if krishna brought 1 pencil and 1 eraser how much would he pay to shopkeeper​

Answer 1

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LOGICAL REASONING

Given that the total cost of 5 erasers, 7 sharpeners and 9 pencils in Rs.100 and the total cost of 2 erasers, 6 sharpeners and 10 pencils is Rs.80. What is the total cost (in Rs.) of one eraser one sharpener and one pencil?

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ANSWER

Suppose one eraser, one sharpener and one pencil cost e,s and p rupees respectively.

Given:

5e+7s+9p=100 ........... (1) and 2e+6s+10p=80 ........... (2)

So, from (2)

e+3s+5p=40 ⟹ e=40−3s−5p

Substituting in (1) we get,

5(40−3s−5p)+7s+5p=40 by solving we get s=10−2p ......... (3)

Substitute in (2) we get,

e−p=10 ........... (4)

Adding (3) and (4) we get,

e+s+p=20.

Hence, option C is correct.

Answer 2

Given :

• A pack of 20 pencils = ₹ 400

• A pack of 17 erasers = ₹ 199

• Krishna bought = 1 pencil and 1 eraser

To find :

• Amount paid by Krishna to the shopkeeper

According to the question :

⟹ 20 pencils = ₹ 400

⟹ 1 pencil = 400 / 20 = ₹ 20

∴ 1 pencil costs ₹ 20.

⟹ 17 Erasers = ₹ 199

⟹ 1 Eraser = 199 / 17 = ₹ 11.7

∴ 1 Eraser costs 11.7

Amount to be paid :

⟹ 1 pencil and 1 Eraser

⟹ 20 + 11.7

⟹ ₹ 31.7

⟹ ₹ 32

So, It's Done !!