mean deviation

The mean life span of an electric bulb is 350 hours, with a standard deviation of 10 hours. A random sample 40 of a particular brand of electric bulbs is taken and found that their mean life span was 348 hours. State the null hypothesis( H o ) for the situation. => H o..

A survey of 139 athletes found that the mean body weight of an athlete is 261.35 pounds. The standard deviation is 2.37, find the 90% confidence interval of the population mean (μ). => 260 < μ < 262 or 261 < μ < 261.70 or 261.02 < μ < 261...

The principal of a school found the mean age of 40 students of one class as 16.50 and that of 50 students of another class as 16. If the standard deviations are 2.83 and 3, find out if their mean ages differ at 99.73% and 98% confidence levels. => the mean ag..

In this series too deviations may be taken either from the actual mean or from standard mean. The calculations will be simplified if the deviation are taken from assumed mean..

Find the z scores of three students who had a score of 93, 80, 84 in an examination for a pre-medicine course which has a mean of 84 and a standard deviation of 4. => 9, - 4, 0 or 23.25, 20, 21 or 2.25, - 1, 0 or - 2.25, 1, 0..

Calculation of Standard Deviation for discrete series - In the discrete series, when deviations are taken from actual mean, the formula ..

Assumed mean = A = 97.5 M = = 97.5 - 1.6 = 95.9 = 96 gm Once you have mastered this method, statistical calculations become very easy. Large values of x are reduced to single digit numbers by Step-Deviation Metho..

A survey asks 'How much time do you spend in front of the TV in one week? Suppose the responses are normally distributed, the mean is 10 hours and the standard deviation is 2 hours. Suppose there are 50 responses to the survey question. How many would you expect to spend between..

The lifetime of certain kinds of electronic devices have a mean of 350 hours and a standard deviation of 20 hours. The distribution is measured to the nearest hour and can be approximated closely to a normal curve. What percentage of electronic devices will have lifetimes from 3..

The mean lifetime of a clock is 30 months. If the distribution is normal with a standard deviation of 4 months, then for how many months should a guarantee be made if the manufacturer does not want to exchange more than 5% of the clocks? => 23 months or 24 months or 20 months or..