<prompt> About test of significance between two large population, one of the following statements is true ?Null hypothesis states that 2 means are equalStandard error of difference is the sum of the standard error of 2 meansStandard error of means are equalStandard error of difference between populations calculated  <response>: Ans. is d i.e., Standard error of difference between populations calculated o If we are concern about a single large population, the test of significance is standard error of mean standard error, which we have already discussed, i.e. If we want to set up confidence limit of a single large population by the data collected by a sample of the population, we calculate standard error 2 SE will cover 95 of values. o But some times we face the problem of comparing results mean between two groups samples whether these two groups represent a single population or two different population. o We proceed to tackle this problem by calculating standard error of difference between two means - SE d. o If the actual difference between two means mean of one sample - mean of second sample is more than twice the standard error of difference between two means calculated by above formula It indicates that the difference is significant and the two samples belong to two different population. 