Consider the value of t such that the area to the left of - t plus the area to t
ID: 3182506 • Letter: C
Question
Consider the value of t such that the area to the left of - t plus the area to the right of t equals 0.1. Assuming the degrees of freedom equals 15. select the t value from the t table. 1.725 1.708 1.753 1.645 The mean life of a television set is 109 months with a variance of 304 If a sample of 110 televisions is randomly selected, what is the probability that the sample mean would be less than 110.2 months? 0.7431 0.7176 0.5132 0.7648 Suppose 52% of the students in a university are baseball players If a sample of 646 students is selected. what is the probability that the sample proportion of baseball players will be greater than 53%? 0.3055 0.3513 0.3332 0.6487 A research scientist wants to know how many times per hour a certain strand of bacteria reproduces He wants to construct the 90% confidence interval with a maximum error of 0.20 reproductions per hour. Assuming that the mean is 6.6 reproductions and the variance is known to be 4.46. what is the minimum sample size required for the estimate? 2974 329 274 302 NASA is conducting an experiment to find out the fraction of people who black out at G forces greater than 6. In an earlier study, the population proportion was estimated to be 0.36. How large a sample would be required in order to estimate the fraction of people who black out at 6 or more Gs at the 99% confidence level with an error of at most 0.02 3822 4041 3610 1648 What happens to the width of a confidence interval for a population mean if the level of confidence is increased without changing the sample size? Assume that the population standard deviation is unknown and the population distribution is approximately normal. Select your answer from the choices below. The margin of error will increase because the critical value will decrease. The increased margin of error will cause the confidence interval to be wider. The margin of error will decrease because the critical value will increase. The decreased margin of error will cause the confidence interval to be narrower. The margin of error will increase because the critical value will increase. The increased margin of error will cause the confidence interval to be wider. The margin of error will decrease because the critical value will decrease. The decreased margin of error will cause the confidence interval to be narrower.Explanation / Answer
Solution1:
Answerc:1.753
Solution2:
P(X bar<110.2) to be found
convert to z variable
z=x-mean/sd/sqrt(n)
z=110.2-109/17.44/sqrt(110)
z=0.723
P ( Z<0.723 )=0.7642
AnswerD
Solution3:
P(p^>0.53)
=0.53-0.52/sqrt(0.52)(1-0.52)/646]
=P(Z>0.509)
( Z>0.509 )=1P ( Z<0.509 )=10.695=0.305
AnswerA
Solution4:
sample size
n=1.645*2sqrt(4.46)^2/0.20^2
=301.72
=302(rounding to nearest integer)
AnswerD