Acertaln type of thread is manufactured With a mean tensrle strength of 72.5 kilograms and a standard deviation of 6.3 kilograms. How is the variance of the sample mean changed when the sample size is (a) increased from 81 to 196? (b) decreased from 324 to 49? (alThe sample variance V from Y for n = 81 ID V fer n = 196 (Type integers or decimals. Do not round.)