mean deviation

Let X denote the number of scores on a test. If X is normally distributed with a mean of 90 and a standard deviation of 10, find the probability that X is not less than 70. => 0.4772 or 0.7472 or 0.7972 or 0.9772..

The local authorities in a certain city install 1600 electric lamps in the streets of the city. If the lamps have a mean life rate of 1000 burning hours, with a standard deviations of 150 hours, find the value of - 2 standards deviations form the mean. Assume..

A sample of scores of 250 candidates has a mean of 47.2 with a standard deviation of 18.6. Find 90% and 95% confidence interval of the population mean and determine which is larger? => (45.3, 49.1) and (44.9, 49.5) and 95% or (45.26, 49.14) and (44.89, 49.51) and 90% o..

Students of a class were given an aptitude test. Their scores were found to be normally distributed with mean 65 and standard deviation 7. What percent of the students scored between in the range 51 - 72? => 47.72% or 81.85% or 34.13% or 13.59%..

30% of the death cases in a hospital are caused by accidents. If 250 cases are selected at random, then find the mean, variance and standard deviation of the number of death cases caused by accidents. => 75, 7.24, 52.5 or 52.5, 75, 7.24 or 7.25, 52.5, 75 or 75, 52.5, 7.24..

The number of ATM transactions of a bank per day were recorded at 12 locations in a city. The mean of the sample was 88.5 transactions, with a sample standard deviation of 42. Find the 98% confidence interval of the true mean. => 19.06 < μ < 157.94 or 78.99 &l..

A mail order firm professional wishes to estimate the average time taken to deliver the packet(s). How large a sample must she select if she desires to be 90% confident that the true mean is within 3 days of sample mean? The standard deviation of the delivery of packet..

Standard Deviation of a statistical data is defined as the positive square root of the arithmetic mean of the squared deviations of items from their arithmetic mean of the series under consideration. The standard deviation is denoted b..

Mr. John gave his students a test in the class. The scores were normally distributed with a mean of 75 and standard deviation of 4. What percent of the students scored between 71 and 79? => 95% or 99.7% or 68% or 34%..

When a distribution is bell-shaped, approximately what percentage of data values will fall within 1 standard deviation of the mean? I. 95% II. 99.7% III. 68% => only III or only I or only II or all are correct..