formula for calculating the variance

The average score of students in statistics examination is 90, with a variance of 4. The average score of students in algebra examination is 102, with a variance of 7. Which course is more variable in terms of scores? => algebra or both are equally variable or cannot be determin..

Calculate empirical formula Use vapour density if given If molecular weight given, calculate 'n' using this formula Molecular formula = n x empirical formula..

Knowing the solubility product of a sparingly soluble salt like AgCl, PbI 2 , BaSO 4 etc. the solubility of the salt can be calculated..

Calculate the percentage by weight of each element. Find out relative number of atoms by dividing percentage of weight by atomic weight. Choose the simplest ratio and the smallest, divide all the ratios by it. If whole numbers are not obtained, then multiply it by a smallest in..

Consider an ideal gas enclosed in a cubical vessel of edge L. Take a corner of the vessel as the origin O and the X-,Y-, Z- axes along the edges (figure 1). Let A1 and A2 be the parallel faces, perpendicular to the X-axi..

The variance of the number of students absent in a day of a particular grade in public schools of 21 are 42 and in private schools of 16 are 20. Are the true variances differ at 90% and 80% confidence levels. => differ at both 90% and 80% or do not differ at both 90% and 80% or ..

If the degrees of freedom of the numerator is 15 and that of the denominator is 24 for testing the variances of two populations using F-test, then find the test value and the critical value at 95% confidence. The sample variances are 45 and 78. => 2.65, 1.83 or 1.73, 2.11 or 2.1..

A random sample of 81 students was tested for the problem solving approach skills. The variance of the scores obtained from the sample was found to be 144. Find the 80% confidence interval for the variance and standard deviation. Assume that the variable is normally distributed...

Find the F-test value for testing the difference between two population variances. The data shows the two samples from each of the populations. => 1.11 or 0.63 or 2.38 or 2.16..

Empirical and molecular formulae of a compound can be determined from the composition of the compound, which is expressed in terms of the percentage of each element present in it. To determine the formula of an unknown compound the following steps are taken: Empirical and molec..