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Ram has 18 coins in the denominations of Rs.1, Rs. 2 and Rs.5. If their total value is Rs. 54 and the number of Rs. 2 coins are greater than of Rs. 5 coins. Then find the number of Rs. 1 coins with him. A) 3 B) 1 C) 2 D) 5 |
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Answer» Correct option is (A) 3 Let Ram has x number of Rs 1 coins, y number of Rs 2 coins and z number of Rs 5 coins. \(\therefore\) x+y+z = 18 ____________(1) \((\because\) Ram has total 18 coins) Their value is Rs 54 \(\therefore\) x + 2y + 5z = 54 ____________(2) Given that number of Rs. 2 coins is more than of Rs. 5 coins. \(\therefore\) y > z ____________(3) \(\because\) Total number of coins is 18. \(\therefore0<x\leq18,0<y\leq18\;\&\;0<z\leq18\) ____________(4) Subtract equation (1) from (2), we obtain y + 4z = 36 ____________(5) By considering inequilities (3) & (4), we can conclude the possible values of y & z. (i) If z = 1, then y = 32 (From (5)) which is contradictions of inequility (4). (ii) If z = 2 then y = 28 which is not possible. (iii) If z = 3 then y = 24 which is not possible. (iv) If z = 4 then y = 20 which is not possible. (v) If z = 5 then y = 16 then y+z = 16+5 = 21 but total coins are 18. Hence, this case is not possible. (vi) If z = 6 then y = 12 then y+z = 6+12 = 18 Then, x = 0 which is not possible because Ram has Rs 1 coin. (vii) If z = 7 then y = 36 - 28 = 82 (From (5)) Then x = 18 - y - z = 18 - 8 - 7 = 18 - 15 = 3 Also x + 2y + 5z = 3+16+35 = 54 (Satisfied) Hence, Ram has 3 Rs 1 coin, 8 Rs 2 coin and 7 Rs 5 coin. Hence, number of Rs 1 coin Ram has = 3. Correct option is A) 3 |
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