编辑代码

# 样本个数
samples_num = 1000
# 随机数个数
random_num = 100
tx = array(dim = samples_num)
for(n in 1 : samples_num){
a = rnorm(random_num)
sum = 0
for(i in 1 : random_num){
tmp = a[i]
sum = sum + tmp^2
}
tx[n] = sum
}

#print(tx);

#tx

opar <- par(no.readonly = TRUE)
hist(tx)
par(opar)

# print(tx)

# 已知概率求t
a <- sort(tx)
# a
print("求得的t为：")
a[250]



# 已知t求概率
c = 0
for(i in 1 : samples_num){
if(tx[i] < 100)
c = c+1
}
a <- sort(tx)
# a
print("求得的概率为：")
c/samples_num