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12 . If a normally distributed random variable has µ = 0 and σ = 1, then 97.5% of the population values lie above:

  1. –1.96.
  2. 1.96.
  3. 1.
  4. –1.


Use the following information to answer the next three exercises. The amount of money a customer spends in one trip to the supermarket is known to have an exponential distribution. Suppose the average amount of money a customer spends in one trip to the supermarket is $72.

13 . What is the probability that one customer spends less than $72 in one trip to the supermarket?

  1. 0.6321
  2. 0.5000
  3. 0.3714
  4. 1

14 . How much money altogether would you expect the next five customers to spend in one trip to the supermarket (in dollars)?

  1. 72
  2. 72 2 5
  3. 5184
  4. 360

15 . If you want to find the probability that the mean amount of money 50 customers spend in one trip to the supermarket is less than $60, the distribution to use is:

  1. N (72, 72)
  2. N ( 72 , 72 50 )
  3. Exp (72)
  4. E x p ( 1 72 )


Use the following information to answer the next three exercises: The amount of time it takes a fourth grader to carry out the trash is uniformly distributed in the interval from one to ten minutes.

16 . What is the probability that a randomly chosen fourth grader takes more than seven minutes to take out the trash?

  1. 3 9
  2. 7 9
  3. 3 10
  4. 7 10

17 . Which graph best shows the probability that a randomly chosen fourth grader takes more than six minutes to take out the trash given that he or she has already taken more than three minutes?

There are 4 uniform distribution graphs. Graph (a) shows a Uniform Distribution from x = 2 to x =  9 with a height of 1/7. The area between x = 6 and x = 9 is shaded. Graph (b) shows a Uniform Distribution from x = 1 to x =  9 with a height of 1/9. The area between x = 6 and x = 9 is shaded. Graph (c) shows a Uniform Distribution from x = 3 to x =  9 with a height of 1/9. The area between x = 6 and x = 9 is shaded. Graph (d) shows a Uniform Distribution from x = 3 to x =  9 with a height of 1/7. The area between x = 6 and x = 9 is shaded.

18 . We should expect a fourth grader to take how many minutes to take out the trash?

  1. 4.5
  2. 5.5
  3. 5
  4. 10


Use the following information to answer the next three exercises: At the beginning of the quarter, the amount of time a student waits in line at the campus cafeteria is normally distributed with a mean of five minutes and a standard deviation of 1.5 minutes.

19 . What is the 90 th percentile of waiting times (in minutes)?

  1. 1.28
  2. 90
  3. 7.47
  4. 6.92

20 . The median waiting time (in minutes) for one student is:

  1. 5.
  2. 50.
  3. 2.5.
  4. 1.5.

21 . Find the probability that the average wait time for ten students is at most 5.5 minutes.

  1. 0.6301
  2. 0.8541
  3. 0.3694
  4. 0.1459

22 . A sample of 80 software engineers in Silicon Valley is taken and it is found that 20% of them earn approximately $50,000 per year. A point estimate for the true proportion of engineers in Silicon Valley who earn $50,000 per year is:

  1. 16.
  2. 0.2.
  3. 1.
  4. 0.95.

23 . If P ( Z < z α ) = 0.1587 where Z ~ N (0, 1), then α is equal to:

  1. –1.
  2. 0.1587.
  3. 0.8413.
  4. 1.

24 . A professor tested 35 students to determine their entering skills. At the end of the term, after completing the course, the same test was administered to the same 35 students to study their improvement. This would be a test of:

  1. independent groups.
  2. two proportions.
  3. matched pairs, dependent groups.
  4. exclusive groups.

A math exam was given to all the third grade children attending ABC School. Two random samples of scores were taken.

n x ¯ s
Boys 55 82 5
Girls 60 86 7

25 . Which of the following correctly describes the results of a hypothesis test of the claim, “There is a difference between the mean scores obtained by third grade girls and boys at the 5% level of significance”?

  1. Do not reject H 0 . There is insufficient evidence to conclude that there is a difference in the mean scores.
  2. Do not reject H 0 . There is sufficient evidence to conclude that there is a difference in the mean scores.
  3. Reject H 0 . There is insufficient evidence to conclude that there is no difference in the mean scores.
  4. Reject H 0 . There is sufficient evidence to conclude that there is a difference in the mean scores.

Questions & Answers

method of collection of data
Abdul Reply
problems of find mean and standard deviation with drawing curve
Kukkuzz Reply
describe the methods of calculation of sample
Anuradha Reply
what are the various uses of statistics in education
Buhari Reply
Survey, Public allocation of federal funds, business analysis and consumer data, the lotto, government programs and special services.
Willard
probability sampling
Rosy Reply
dicuss probability sampling
Rosy
given that a sample is normally distributed with M=10 sd=8 determine
Rosy
disscuss probability sampling
Rosy
Discuss probability sampling
Rosy
What is mean
Rosy
Probability sampling is based on the fact that every member of a population has a known and equal chance of being selected. For example, if you had a population of 100 people, each person would have odds of 1 out of 100 of being chosen. With non-probability sampling, those odds are not equal.
Willard
The Arithmetic Mean is the average of the numbers: a calculated "central" value of a set of numbers.  To calculate it:  • add up all the numbers, • then divide by how many numbers there are. Example: what is the mean of 2, 7 and 9? Add the numbers: 2 + 7 + 9 = 18 Divide by how many numbers, 3 you
Willard
get 6
Willard
guidelines of designing a table
Anuradha
you can find that information on this website there is a lot of information. It's about interpreting what the concept of information & data you are getting from the graph and understanding how to read the graph and analyze the information. ***understandinggraphics.com/design/data-table-design/
Willard
find X and Y so that the ordered data set has a mean of 38 and median of 35 17, 22, 26, 29, 34, X, 42, 67 , 70, Y
Mohamed
Frequency find questions
Rimsha Reply
?
Rosy
What is nominal variable
olusola Reply
Write short notes on, nominal variable, ordinal variable, internal variable, ratio variable.
olusola
P( /x-50/ less than or equal to 5 ) where mean =52 and Variance =25
Jay Reply
how I get the mcq
Mukesh Reply
please what is data mining
Josephine Reply
the exploration and analysis of large data to discover meaningful patterns and rules
Hussein
how do we calculate the median
All Reply
f(x)=cx(1-x)^4 as x range 4rm 0<=x<=1. Can someone pls help me find d constant C. By integration only..
Akeem Reply
uses of statistics in Local Government
Saleema Reply
Hi
Tamuno
hello
Saleema
state road transport corporation
Atul
District statistical officer
Atul
statistical services
Atul
Please is this part of the IMT program
Tamuno
testing of drugs
Shambhavi
hii 2
Qamar-ul-
How about population census
Tamuno
Hello every one
Okoi
sample survey is done by local government in each and every field.
syeda
statistics is used in almost every government organisations such as health department, economic department, census, weather forecasting fields
raghavendra
that's true
syeda
statistics is one of the tool that represents the falling and rising of any cases in one sheet either that is in population census whether forecast as well as economic growth
Aadil
statistic is a technique, and statistics is a subject
syeda
what is business statistics
PM Reply
Probability tells you the likelihood of an event happening. ... The higher the probability, the more likely it is to happen. Probability is a number or fraction between 0 and 1. A probability of 1 means something will always happen, and a probability of 0 means something will never happen...
La Reply
Saying it's a number between zero and one means it is a fraction so you could remove "or fraction" from you definition.
Carlos
wouldn't be correct to remove fractions, saying a number is justified as probabilities can also be decimals between 0 and 1.
Denzel
Saying "a number" will include it being a decimal which are themselves fractions in another form.
Carlos
I will simply say a probability is a number in the range zero to one, inclusive.
Carlos
f#$
Carlos
How to delete an entry? This last one was a pocket print.
Carlos

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Source:  OpenStax, Introductory statistics. OpenStax CNX. May 06, 2016 Download for free at http://legacy.cnx.org/content/col11562/1.18
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