Sampling Distribution of a Proportion - Page 3

Questions

Of 800 people surveyed, 420 were male, and 325 had cell phones. Of those with cell phones, 200 were female. What is the probability that a person surveyed was either male or had a cell phone?
Of 800 people surveyed, 420 were male, and 325 had cell phones. Of those with cell phones, 200 were female. What is the probability that a person surveyed was either male or had a cell phone?
Can someone help me solve this problem?
1) what proportion of boys and girls should be selected? 2) How many boys and girls should be selected for a stratified random sample of 30 students? Explain how to obtain this sample question.
A survey of 200 people found that 20 of them played chess . In a pie chart , what would be the sector angle of this group?
A proffesional wishes to estimate the birth weights of a baby. How large a sample must she select if she decides to be 99% confident that the true mean is within 10 ounces of the sample mean? The standard deviation of the birth weights is 4 ounces.