概率問題? 不明白

P (A win)
= P (A1) + P (A0B0A1) + P (A0B0A0B0A1) ..... <---------- (A1 means A throws 1)
= 1/2 + (1/2)^3 + (1/2)^5 ......

The summation follows the geometric series:
First term a = 1/2
Common ratio d = (1/2)^2 = 1/4

By the formula of sum to infinity:
P (A win)
= 1/2 + (1/2)^3 + (1/2)^5 ......
= a / (1 - d)
= (1/2) / (1-1/4)
= (1/2) / (3/4)
= 2/3

P(能夠解決問題的概率)= 1 - (唔可以解決問題的概率)
p= 1- 4/5x2/5
p=1-8/25
p=17/25

製造商每年生產物品的成本包括固定成本$130,000 和每件物品不固定成本
$8 。若每件物品的售價為$15，製造商需要賣出多少物品才能取得$150,000
之利潤?

Solution

Let X be the number of goods required.

成本= 130,000 + 8X
收入= 15X

利潤 = 15X - (130,000 + 8X) =7X -130,000

Therefore, we have 7X -130,000 = 150,000
7X = 280,000
X = 40,000

要賣出40,000物品才能取得$150,000 之利潤