1) When the length of a cube is increased, its total surface area is increased by 50%. What is the percentage increase of its volume?
2)The number of $5 coins is less than that of $2 coins by 10. If the total value of coins cannot exceed $160, what is the least total value of the coins?
Maths (With steps)
2008-07-08 2:10 am
回答 (1)
2008-07-08 2:32 am
✔ 最佳答案
1) Let length of cube be h. Surface area = 6h^2 and volume = h^3.Let new length of cube = H. So surface area = 6H^2.
Now 6H^2 = (1+50%)(6h^2) = 1.5(6h^2), therefore H = sqrt(1.5)h. Therefore new volume = [(1.5)^3/2]h^3. Therefore, percentage increase in volume
= (1.5^3/2 - 1) x 100% = 83.7%.
2) The least total value is when $2 coin is 11 and $5 coin is 1 (if zero is not allowed),therefore least value is $27.
收錄日期: 2021-04-25 22:36:09
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