8.1

15

  1. large sample size indicates that the sampling distribution is approximateley normal using central limit theoram

  2. if we take 100 random samples about 7 samples have the probability to have a mean that is greater than 83

  3. if we take 100 random samples about 2 samples have the probability to have a mean that is less than or equal to 75.8

  4. if we take 100 random samples about 78 samples have the probability to have a mean between 78.3 and 85.1

17

  1. if the population is normally distributed, then the sampling distribution of x bar is exactly normal

  2. if 100 random samples of n=12 are taken from the population which are noramlly dstributed, about 75 of these samples will have a mean less than to 67.3

  3. if 100 rando samples of n=12 are taken from the population which are normally distributed, about 41 of these samples will result n a mean greater than or equal to 65.2

19

  1. 35% would last less than 260 days

  2. sampling distribution of x bar is normal

  3. if we take 100 simple random samples, then about 5 of the samples will result in a mean gestation period equal to or less than 260; n = 20

  4. out of 1000 random samples about 4 samples will result in mean gestation period of 260 or less; n = 50

  5. we can conclude the sample is likely from a population whose mean period is less than 266 days

  6. if 100 simple random samples are taken n =15, 98 of the samples will result in period between 256 and 276 days

21

  1. about 31 students

  2. about 4 students

  3. about 7 students

  4. because x bar is greater than 95 because standard deviation decreases and n increases

  5. about 11 students; doesnt qualify as unusual

  6. c=93.7; Z score= 1.645

23

  1. about 57 of the months

  2. about 73 of the samples

  3. about 81 of the samples

  4. about 85 of the samples

  5. the probability of earning to be positive rate of return increase as the investment time increases

8.2

11

  1. p is distributed approximately normal

  2. about 19 of 100 will result in 63 or greater indivifuals

  3. around 5 out 1000, will result in 51 or fewer individuals

12

  1. The distribution is approximately normal

  2. about 19 out of a 100 random samples, will result in more individuals with this characteristic.

  3. about 75 of of a 100 random samples, will result in 150 more individuals with this characteristics.

13

  1. distribution of p is approximately normal

  2. about 4 of 1000 people, result in 390 or more individuals

  3. about 2 of 100 people, qill result in 320 or fewer individuals

14

  1. approximately normal

  2. about 19 of the 100 random samples will have the charestic

  3. -0.2843

15

  1. Qualitative since you can either order or not order a meal in foreign language

  2. since it varies from sample to sample, source is the individuals in the sample and the ability to order a meal in foreign language

  3. less than 5%, and distribution is approximately normal

  4. about 20 of 1000 samples will result in a sample where greater than 50% can order a meal in a foreign language

  5. about 2 of 100, will result in a samle where 80 or fewer can order in foreign language, the result is unusual

16

  1. qualitative

  2. the source of varibility are the americans asked whether they are satisfied or not

  3. approximately normal

  4. 0.2418

  5. yes

17

  1. approximately normal

  2. about 32 out of 100 random samples will result in less than 38% who believe marriage is obselete

  3. about 32 out of 100 random samples, will have between 40% and 45% where respondents believe marriage is obsolete

  4. 8 out of 100, will have atleast 210 respondents who sayy that marriage is obsolete