数学T paper 2讨论专区

Lov瑜瑜4ever

回复  Lov瑜瑜4ever


    这个我不知道你的书，我还在想着
原本刚才写了很长的，然后我改了因为那个题 ...
junchung2003 发表于 10-12-2010 12:21 PM

是咯。。。我也是这么觉得。。。哈哈。。。

peaceboy

回复 579# Lov瑜瑜4ever


    math T不是很熟，等log来解

不过应该是P(x>3.92)的意思

Lov瑜瑜4ever

回复  Lov瑜瑜4ever


     math T不是很熟，等log来解

不过应该是P(x>3.92)的意思
peaceboy 发表于 10-12-2010 03:46 PM

可是问题是P(x<q),又不是P(x>q)...

whyyie

大家帮帮忙... STPM时他们给的那本红色书( 有很多table的)叫什么名...哪里有卖.

我都没用过, 考paper 2时怕不会用...

Log

回复 575# Lov瑜瑜4ever
3.92不是答案吧。。。
问题应该问少了 find the values of q in each P(x<q)=1/4 and P(x>q)=1/4

Log

回复 584# whyyie

你是指normal distribution table?

whyyie

回复 586# Log

应该是咯...有很多table的, 惨了我从来没有用过...

Log

回复 587# whyyie
有很多table的，前面的table我们不必用，因为用计算机算就用ok，（如果你要用也可以）（前面的那些log， ln , exponent 等等）
后面就是statistics 的 etc. normal distribution table

海涵

f(x)= 1/25(1-2x),   -2<x<1/2
        3/25(2x-1),   1/2<x<3
        0             ,   otherwise

given that P(0 < x < k) = 13/100,determine the value of k.

nkrealman

f(x)= 1/25(1-2x),   -2
海涵 发表于 11-12-2010 12:09 PM

  k 有 decimal ，对吗？0.908...刚觉不太对劲。。。我再做看
从0 到 1/2 probability is 1/100 而已，所以 k 是大过 1/2

所以从 1/2 到 k 的 probability 是 2/100

而从 -2 到 1/2 的probability 是 25/100

所以 conclusion 从 -2 到 k 的probability 是 27/100

然后 integrate f(x) from -2 until 1/2 + integrate 1/2 until k=27/100

nkrealman

it has been found that 65% of women over 50 years old suffers from osteoporosis.8 women were randomly chosen from a group of women over 50 years old.find the probability that out of these 8women,more than 6 of them suffered from osteoporosis.(这个找到）

20% of women suffering from osteoporosis recovers after 2 years.if 3 women of age over 50 years old were randomly chosen,find the probability that none of them suffered from osteoporosis....

nkrealman

research shows that 40% of malaysians prefer tea,35% prefer coffee and the rest prefer milk.9 person were randomly chosen.find the probability that

a.the same number of people prefer each type of drinks.
b.more people prefer tea to the other two drinks

junchung2003

回复 592# nkrealman


    a. 4.288 * 10^(-5)
b. 3.4568 * 10^(-3)

答案是这个吗？

nkrealman

回复  nkrealman


    a. 4.288 * 10^(-5)
b. 3.4568 * 10^(-3)

答案是这个吗？
junchung2003 发表于 11-12-2010 09:03 PM

不是
a.0.07203
b.0.2666

nkrealman

再来

the life of a certain brand of washing machine is normally distributed with a mean of 3000 hours and a S.D of 1000 hours.

a.calculate the probability that a machine chosen at a random,last less than 1000 hours.（找到了）

b. the total time of customers using the machine in 2 years has another normal distribution with mean 800 hours with S.D 200 hours.the washing machine is guaranteed for the 1st 1000 hours.calculate the percentage of the customers whose machine is returned under guarantee within the 1st 2 years...

Lov瑜瑜4ever

The continuous random variable X takes values in the interval 0 until 3.
If P(X>x)=1-(1/27)(x^3) for 0<x<3.
Find the c.d.f , F(x).
在 0<x<3 时的F(x)要怎样找？？

nkrealman

The continuous random variable X takes values in the interval 0 until 3.
If P(X>x)=1-(1/27)(x^3) fo ...
Lov瑜瑜4ever 发表于 11-12-2010 10:28 PM

   从 0 到 3.。。就是 F(3)

Lov瑜瑜4ever

从 0 到 3.。。就是 F(3)
nkrealman 发表于 11-12-2010 10:31 PM

然后呢？？

peaceboy

回复 591# nkrealman


   
it has been found that 65% of women over 50 years old suffers from osteoporosis.8 women were randomly chosen from a group of women over 50 years old.find the probability that out of these 8women,more than 6 of them suffered from osteoporosis.(这个找到）

20% of women suffering from osteoporosis recovers after 2 years.if 3 women of age over 50 years old were randomly chosen,find the probability that none of them suffered from osteoporosis....

你有没有少写什么

P(not suffer) = 0.35
P(suffered and recover) = 0.65*0.2
                                 = 0.13
p(not suffer u suffered and recover) = 0.48

3C0 (0.52)^0 (0.48)^3 = 0.11052

peaceboy

回复 592# nkrealman

research shows that 40% of malaysians prefer tea,35% prefer coffee and the rest prefer milk.9 person were randomly chosen.find the probability that

a.the same number of people prefer each type of drinks.
b.more people prefer tea to the other two drinks

a) (0.4)^3 (0.35)^3 (0.25)^3 * 9!/(3！3！3！)

b) P(tea) = 0.4
P(other) = 0.6

9C5 0.4^5 0.6^4 + 9C6 0.4^6 0.6^3 +9C7 0.4^7 0.6^2 + 9C8 0.4^8 0.6^1 + 9C9 0.4^9 0.6^0