Quiz 13.2

What z score separates the top 70% from the bottom 30%?

-.52

John drives to work each morning and a trip takes on average M = 38 minutes. The distribution of the driving times is approximately normal with with a of SD = 5 minutes. For a randomly selected morning, what is the probability that John's drive to work will take between 36 and 40 minutes?

.3108

A multiple choice test with 48 questions has four choices for each question. What is the probability of getting more than 12 questions correct by just guessing? (round your z score to nearest 2 decimal places)

.4325

What proportion of a normal distribution is located between z = -1.5 and z = +1.5

.8664

Population M = 60 and SD = 8 is transformed into z scores, the M and SD of z score will be

0 and 1

Sample of n=9 came from a pop. with μ=40 and ς=6, What's the prob. that M>43?

0.0668

Sample n=16 is selected from pop. of μ=100, ς=32. If M=104, what's the z-score?

0.5

If you score 75 on a test where the M = 70. Which SD would give you the highest position?

1

From a deck of cards (52), what is the probability to draw a card that is black AND Jack?

1/26

You got a score of 65 on an exam with M = 70, which SD gives you the best position?

10

A jar contains 10 red marbles and 10 blue marbles. A random sample without replacement of n = 3 marbles is selected from the jar. If the first 2 marbles are both blue, what is the probability that the third marble will be red?

10/38

A population distribution has SD = 6. What position in this distribution is identified by z = 2?

12 points above the mean

A population of N = 100 had M = 30 and SD = 4. What's the s2?

16

If I roll 2 dice (6 sides), what's the probability of getting an odd number less than 5?

2/36

If I roll 2 dice, what's the probability of getting 12 or 2?

2/36

A population has M = 50, what SD would make x = 55 a more central score?

20

A population has SS = 100 and s2 = 4. What's the N?

25

The SS = 20 for a population of N = 5. What is the s2?

4

SAT has a M = 500 and SD = 100. If EKU accepts top 60% on a SAT , what's the minimum acceptance score?

475

In a population with SD = 8, a score of x = 44 corresponds to z = -.05. What's the M?

48

A sample pf N = 8 has SS = 50. If the same scores were a population, the SS would be?

50

A sample of n=9 has SE of 8. For the same population, n=16 would have SE of?

6

For a sample with SD = 12, a score of x = 73 corresponds to z = 1. What's the sample mean?

61

A sample n=4 came from pop. μ=70 and ς=8. If the M maps to z=2, what's the value of M?

78

For a population with μ=80 and ς=20, a sample of 16 will have an expected value and SE of?

80; 5

What happens to the standard error as sample size increases?

Decreases

Under what circumstances is the distribution of sample means normal?

If the population distribution is normal and the sample size is greater than 30

A population has M = 50 and SD = 5. If every score is multiplied by 3, new M and SD are?

M = 150 and SD = 15

For a sample of N = 30, x = 45 maps to z = 1.5 and x = 40 maps to z = 1. What's the M and SD?

M = 30, SD = 10

For a population with μ=40 and ς=10, which sample is least likely to be obtained?

M=42; n=4

The smallest score in a population is 5 and the largest score is 10. You can conclude that...

SD is smaller than 5

What are the values for SS and s2 for sample 1,4,7?

SS = 18, s2 = 9

What are the values for SS and s2 for sample 1,1,0,4?

SS = 9, s2 = 3

A sample of 36 was selected from a population with normal dist. Which of the following is true?

The distribution of sample means will form a normal distritbution.

What term is used to identify the mean of the distribution of sample means?

The expected value of M

Last week Sarah had exams in math, English, and Spanish. On the math exam, mean was 30 with SD = 5, and Sarah had a score of x = 45. On the Spanish exam, the mean was 60 with SD = 8, and Sarah had a score of x = 68. On the English exam, the mean was 70, SD = 8, and Sarah had a score of x = 70. For which class should Sarah expect the better grade?

math

A true/false test has 100 questions. What's the chance of getting more than 55 correct by guessing?

p(x>=55.5)

A population with μ=80 and ς=10, what's the prob. of getting M>75 for a sample of n=25?

p=0.9938

The direct, unchanged scored that are the direct result of measurement are called

raw scores

Under what circumstances is the score that is 5 points above mean, relatively close to the mean?

when the population standard deviation is much greater than 5

Which of the following represents the deviation score?

x - u