Statistics and Probability Answers

A sample of size 60 is taken from a population of chocolate balls. The weights of chocolate

balls are normally distributed with a mean of 40 g and a standard deviation of 8 g.

a. Find the parameters for this distribution of the sample mean.

b. Find the probability that the sample mean is between 38 g and 42

A machine fills boxes with chocolate balls. The weights of the empty boxes are normally

distributed with a mean of 150 g and a standard deviation of 10 g. The mean weight of each

chocolate ball is 40 g with a standard deviation of 0.8 g. A full box contains 25 chocolate balls.

  At a professional examination students were getting grades A, B, C, D and E in the ration of 1:3:4:5:7 In the last examination 600 students who took the revision block release classes, were graded as follows:

Grade

A

B

C

D

E

Number of Students

50

100

130

150

170

By using the Chi Square, check if there is an improvement in student’s performance after taking revision block release classes at 0.05 level of significance and advice the examination board?

1. Why it is dangerous to make predictions beyond the scope of what you have observed in your data set

2. give at least two examples of situations where in predictions of the value of the dependent variable using the equation of the regression line would be meaningless

Sales personnel for X Company are required to submit weekly reports

listing customer contacts made during the week. A sample of 61 weekly contact

reports showed a mean of 22.4 customer contacts per week for the sales personnel.

Two balls are drawn in succession without replacement from an urn containing 4 red balls and 3 black balls. Find the probability distribution of the number of black balls.

Briefly explain the following topics with the help of example.

• Discrete Probability
• Continuous Probability
• Normal Distribution
• Hypergeometric Distribution
• Poisson Distribution

What is Probability? Briefly explain with the help of diagram?

Sketch the scatter plot of the following that shows

1. Strong positive correlation

2. Weak positive correlation

3. Perfect negative correlation

4. No correlation

Find the mean of probability distribution of the random variable X, which can take only the values 2,4,5 and 9, given that P(2) = 9/20, P(4) = 1/20 , P(5) = 1/5 , and P(9) = 3/10