F.1 EXAM MATHS QUESTIONS

[匿名]

2014-01-17 6:58 pm

I HAVE SOME QUESTIONS ABOUT MATHEMATICS

Gloria has some coins. The number of $5 coins is 37.5% more that the number
of $1 coins and the value of $5 coins is $3 less than seven times the value of $1
coins.
(a) Find the number of $1 coins.
(b) Find the total value of all coins.
(c) To minimize the number of coins ,Gloria exchanged all the coins with Alex
into $10 coins ,$5 coins and $2 coins . Find the change in the number of coins
after the exchange.

THANKS

回答 (1)

用戶4366

2014-01-18 9:13 am

✔ 最佳答案

Let there be x $5 coins and y $1 coins.

Because [The number of $5 coins is 37.5% more that the number
of $1 coins]

x = (1+0.375)y

x = 1.375y .......... (1)

Because [ the value of $5 coins is $3 less than seven times the value of $1
coins. ]

5x + 3 = 7y ......... (2)

Sub. (1) into (2)

5(1.375y) + 3 = 7y
6.875y + 3 = 7y
3 = (7-6.875)y = 0.125y
y = 3/0.125 = 24

Sub into (1)
x = 1.375y = (1.375)(24) = 33

a) There are 24 $1 coins

b) Total values = (33)(5) + (24)(1) = 189

c)Because [ minimize the number of coins ]
After exchange, there are :
18 X $10
1 X $5
2 X $2

Total number of coins before exchange = x+y = 33 + 24 = 57

Total number of coins after exchange = 18 + 1 + 2 = 21

Change in the number of coins = 57 - 21 = 36

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