[question revoved by admin]

I am not sure what formula Elans used… isn’t the formula that should be used is below?

avgVariance*[(1-correlation)/n +correlation] ?

according to me the answer was below

for A 0.22 * ( (1-0.15)/10 +0.15) = 0.0517

for B 0.22 * ( (1-0.15)/200 +0.15) = 0.0339