In x linked recessive if the mother is carrier and father is normal and their first child is male and is affected the next child is female, how much chances are there that she will be carrier?

A 50% chance I believe. The mother will always give the X chromosome and since the father is normal and doesn't carry that ressecive trait they can only get it from the mother. (I'm not completely sure!))

i think the answer is 95 hope this

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.