1) Suppose a poll of 20 voters is taken in a large city. The purpose is to determine the numbers who favor a certain candidate for mayor. Suppose that 60% of all the city’s voters favor the candidate.
Find the following:
i. Find the mean and standard deviation of x. Answer: mean=12 and standard deviation=2.19
ii. Find the probability that x<=10 Answer: 0.245
iii. Find the probability that x>12. Answer: 0.416
iv. Find the probability that x=10. Answer: 0.159
I assumed that by x the question means the number of voters. I'm not sure how to get the answer for ii, iii and iv. I used the nCxp^xq^(n-x) formula but maybe I'm taking the wrong values for n and x. Can someone explain the correct way to work-out ii-iv ?
2) The grade - point average score of 80 student of Department of Computer Science of Dhaka University in their term final examination was found to follow approximately a normal distribution with a mean of 2.1 and a standard deviation 0.6. How many of the students are expected to have a score between 2.5 and 3.5? (Answer: 20)
As for this one, I've no clue how to find the number of students- I found all the z-values and all but how will that help me to to find the numberof students expected to have a score between 2.5 and 3.5? What's the work-out for this one?
Find the following:
i. Find the mean and standard deviation of x. Answer: mean=12 and standard deviation=2.19
ii. Find the probability that x<=10 Answer: 0.245
iii. Find the probability that x>12. Answer: 0.416
iv. Find the probability that x=10. Answer: 0.159
I assumed that by x the question means the number of voters. I'm not sure how to get the answer for ii, iii and iv. I used the nCxp^xq^(n-x) formula but maybe I'm taking the wrong values for n and x. Can someone explain the correct way to work-out ii-iv ?
2) The grade - point average score of 80 student of Department of Computer Science of Dhaka University in their term final examination was found to follow approximately a normal distribution with a mean of 2.1 and a standard deviation 0.6. How many of the students are expected to have a score between 2.5 and 3.5? (Answer: 20)
As for this one, I've no clue how to find the number of students- I found all the z-values and all but how will that help me to to find the numberof students expected to have a score between 2.5 and 3.5? What's the work-out for this one?