Question

Sara had some 2-rupee and 5-rupee coins in her money box. She exchanged them for some 10-rupee coins. If the number of 5-rupee coins is one less than the number of 2-rupee coins, then find the number of 5-rupee coins.​

Answer 1

Step-by-step explanation:

A boy has a 5 rupees coin, 2 rupees coin, and 1 rupee coin in ratio of 3:4:5. If he has an amount of ₹224, how many 1 rupee coins does he have?

Let the total number of coins be 12X.

Then,

Number of Rs.5 coins = 3X

Number of Rs.2 coins = 4X

Number of Re.1 coins = 5X

Total value of :-

Rs.5 coins = 3X * 5 = 15X

Rs.2 coins = 4X * 2 = 8X

Re.1 coins = 5X * 1 = 5X

Given, total value of all coins = 224

Therefore,

15X + 8X + 5X = 224

28X = 224

X = 8

Total number of coins = 12X = 12 * 8 = 96

Number of,

Rs.5 coins = (3/12) * 96 = 24 coins

Rs.2 coins = (4/12) * 96 = 32 coins

Re.1 coins = (5/12) * 96 = 40 coins

(Given no. of Rs.5, Rs.2, and Re.1 coins are in the ratio of 3:4:5)

Final Answer : The sara has 40 Re.1 coins.

Let's cross verify the answer once.

(24*5) + (32*2) + (40*1)

= 120 + 64 + 40

= 224 = Value given in the question.

Answer 2

Answer:

Let the number of 2-rupee coins be x.

Then, the number of 5-rupee coins will be x - 1

Total amount of 2-rupee coins = ₹2 * x

= ₹2x

Total amount of 5-rupee coins = ₹5 * ( x-1 )

= ₹5x - 5

Total amount in money box = ₹2x + ( ₹5x - 5 )

= ₹ 7x -5

{ if we have to make this amount a multiple of 10 then ₹2 's quantity should be a multiple of 10, and the quantity of ₹5 should be even to be a multiple of 10 }

Therfore, the quantity of ₹2 coins can be 5  (₹2 * 5 = ₹10, a multiple of 10)

and

₹5 coins is 1 less than the quantity of ₹2 coins so

The number of ₹ 5 coins will be  = (5 - 1)

=  4

{ checking, (₹2 * 5) + (₹5 * 4) = ₹10 + ₹20 = ₹30

and ₹ 30 is a multiple of 10 }

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Step-by-step explanation: