GWD 19-10

[dibert8]

Q10:
If $1,000 will be deposited in a bank account and I is the dollar amount of interest earned from the original deposit, represented as I = 1000 {(1 + r/100)^n – 1}, and the annual interest rate is r percent, is r > 8 percent?
(1) The deposit earns a total of $210 in interest in the first 2 years.
(2) (1 + r/100)^2 > 1.15




Ans: D
可是仔細一算,有點問題也!
(1) n = 2, I = 210, 可求出 r, 所以可以確定 r 是否 > 8
(2) r = 8 代進去 => I = 1.1664 >1.15, 所以不確定 r 是否 > 8 (i.e. r > 7.x#@ 就會使得 I > 1.15)
答案應該是 (A)

[Yimmiwan]

問題是問 r 是否大於8%，你的兩個算法都沒有錯，所以你對第二項條件的推理證明了 r 不大於8%，所以成功的回答了題目的問題，所以兩個條件都可以，選擇D。

希望這樣的解釋夠清楚

[steven31228]

Q10:
If $1,000 will be deposited in a bank account and I is the dollar amount of interest earned from the original deposit, represented as I = 1000 {(1 + r/100)^n – 1}, and the annual interest rate is r percent, is r > 8 percent?
(1) The deposit earns a total of $210 in interest in the first 2 years.
(2) (1 + r/100)^2 > 1.15




Ans: D
可是仔細一算,有點問題也!
(1) n = 2, I = 210, 可求出 r, 所以可以確定 r 是否 > 8
(2) r = 8 代進去 => I = 1.1664 >1.15, 所以不確定 r 是否 > 8 (i.e. r > 7.x#@ 就會使得 I > 1.15)
答案應該是 (A)

我也覺的是A
題目不是問是否 r > 8 percent?
正如大大所言
(1) 當 r=8, I = 1.1664 >1.15 所以r是大於8
(2) 當 r=7.XX I就可以大於1.15 所以r不是大於8
所以沒辦法確定r是否> 8 percent
我認為這題是A沒錯

[chikm]

做PP有做到這題..答案的確是A