When conducting a t-test for independent samples we have 2 ways of computing the variance. One way is to compute the variance for each sample, but this only works if the samples are the same size. If the samples are different sizes, we use a different equation. What is this variance equation that should be used if the two samples are not the same size?

Q: Give two ways to compute the variance of a continuous random variable.

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Q: then the value of variance of X is

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