包含代數 .百分率.
1. Ann had a bag of glass beads. She used half of the beads to make a necklace. She and her sister then use 1/6 and 1/7 of the original number od beads respectively to make two bracelets. If there are 16 glass left, find the original number of glass beads.
2. Two shops sell the same brand of chocolate at the same price. Today they both cut down its price. Shop A decreases the price by 30%, and increases by 30% after a week. Likewise, shop B decreases its price by 40%, and increases by 40% after a week. Are the price of the chocolate at the two shops still the same after a week?
我想要式同答案`
Thx a lot.
10點!! ]] 中一英文數學 Qx2
2009-07-16 7:38 pm
回答 (2)
2009-07-16 8:04 pm
✔ 最佳答案
1. Let x be the original no. of beads. Thenx-x/2-x/6-x/7 = 16
(42x-21x-7x-6x)/42 = 16
8x/42 = 16
x = 84
The original no. of beads is 84
2. Let $x be the original price of chocolate for the two shops
Shop A's price after a week = $x*(1-30/100)*(1+30/100)= $0.91x
Shop B's price after a week = $x*(1-40/100)*(1+40/100)=$0.84x
Therefore the prices of chocolate for the two shops will not be the same after a week.
2009-07-16 8:06 pm
1.Let the original number of glass beads be n.
n/2 =1/6n + 1/7n + 16
21n=7n+6n+672
8n=672
n=84
2.Let the original price be $y.
The price of the chocolate after a week in Shop A
=y(1-30%)(1+30%)
=0.91y
The price of the chocolate after a week in Shop B
= y(1-40%)(1+40%)
=0.84y
∴The price of the chocolate at the two shops are not the same after a week.
n/2 =1/6n + 1/7n + 16
21n=7n+6n+672
8n=672
n=84
2.Let the original price be $y.
The price of the chocolate after a week in Shop A
=y(1-30%)(1+30%)
=0.91y
The price of the chocolate after a week in Shop B
= y(1-40%)(1+40%)
=0.84y
∴The price of the chocolate at the two shops are not the same after a week.
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