# 請問一下統計題目(代PO~20點)~謝謝~!!!

1.A random sample of size 100were selected from a population with mean 10 and variance 9.Find the mean and standard deviation of the sampling distribution of the sample mean and also find the probability that sample mean is less than 10.2 ???

2. A survey was taken of 313 children,ages 14 to 22 years,from among the children

of the nation top execcutives.When asked to identify the best aspect of being are of

this privileged group,55% mentioned material and financial advantages.Suppose that the

proportion P of children in the porulation is actually cqual to 0.5 What is the probability of observing a sample proporion as large as or larger than the observed P=0.55???

3. Twelve neasurements were randomly selected from a normal population with mean and standard deviation,125.12 and 12.3,respectively.fond P(X>130)???

### 2 個解答

• 最佳解答

1.

E(X_bar)=10

SE=√(9/100)=0.3

p(X_bar<10.2)=p(Z<(10.2-10)/0.3)=p(Z<0.67)=0.7486

2.

p(p>0.55)=p(Z>(0.55-0.5)/√(0.5*0.5/313))=p(Z>1.77)=0.0384

3.

p(x>130)=p(Z>(130-125.12)/12.3)=p(Z>0.4)=0.3446