1. At a certain concert, 61% of audience was under 20 years old. A random sample
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Question
1. At a certain concert, 61% of audience was under 20 years old. A random sample of n = 175 members of the audience was selected. Find the value of sample mean, the mean of the distribution of sample proportions.
2. According to one pollster, 59 % of people are afraid of flying. Suppose that a sample of size 20 is drawn. Find the value of standard error , the standard deviation of the distribution of sample proportions.
3. It has been reported that 48% of teenagers play video games on their phones. A random sample of 60 teenages is drawn. Find the probability that the proportion of teenagers in the sample who play video games on their phone is less than 0.490.
4. 74% of freshmen entering public high schools in 2006 graduated with their class in 2010. A random sample of 81 freshmen is selected. Find the probability that the proportion of students who graduated is greater than 0.747.
Explanation / Answer
1. At a certain concert, 61% of audience was under 20 years old. A random sample of n = 175 members of the audience was selected. Find the value of sample mean, the mean of the distribution of sample proportions.
2. According to one pollster, 59 % of people are afraid of flying. Suppose that a sample of size 20 is drawn. Find the value of standard error , the standard deviation of the distribution of sample proportions.
3. It has been reported that 48% of teenagers play video games on their phones. A random sample of 60 teenages is drawn. Find the probability that the proportion of teenagers in the sample who play video games on their phone is less than 0.490.
4. 74% of freshmen entering public high schools in 2006 graduated with their class in 2010. A random sample of 81 freshmen is selected. Find the probability that the proportion of students who graduated is greater than 0.747.
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