Mathematical Properties of Arithmetic Mean

The income of a group of 10,000 persons was found to be normally distributed with mean Rs.750 per month and a standard deviation of Rs. 50, show that of this group about 95% has income exceeding Rs. 668 and only 5% had income exceeding Rs. 832. (area between 750 and 668 = 0.4495, area between 750 and 832 = 0.4495).

Exponential Distribution

The means of two large samples of sizes 1000 and 2000 are 67.5 and 68.0 respectively. Test the quality of the means of the two populations each with standard deviation of 2.5. (z table value at α0.05= -1.96).

Time Series Analysis

Stratified Sampling

Why is forecasting so important in business? Explain the application of forecasting for long term decisions.