Question

23. The national average SAT score (for Verbal and Math) is 1019. If we assume a normal distribution with o= 100, a. what SAT score is in the 85th percentile? b. what is the probability that a randomly selected score exceeds 1200? 26. Ten randomly selected people were asked how long they slept at night. The mean time was 7.1 hours, and the standard deviation was 0.78 hour. Assume that the data is normally distributed a. For a 95% confidence level, find the margin of error. Round to two decimal places. b. Construct a 95% confidence interval of the mean time. Interpret your results. 27. In a Gallup Poll of 1005 individuals, 452 thought they were worse off financially then a year ago. Round sample proportion to two decimal places.

Answer 1

Answert Pq Noro Given dakar 95 The national average SAT Score Ps 1019. 1. Mean u = 1019 que assume a normal standard distrabukion 0-100 - we know that P( x < 4) - (2 <(A - )/6) @ The SAT score is in the 85th porcentile. So, P(x <A=0.85 PCZCIA -1019) 1100) - 0.86 (:From standard normal distribution table), The value corresponding to the probability of 0.85 is 1.04 (A-1019) 1100 -1.04 A =1193, -The SAT score of the 85th percentile is 1123. © The probability that a randomly selected score exceeds 1200. =P(x>1200). = 1-PCX51200) =+-P(23(1200.-2019)/100) 1-P(Z <1.81)

21-09649 = 0.0351, 1. The probability that a randomly selected exceedi 1900 -0.0391, score