# 0.2 Practice tests (1-4) and final exams  (Page 35/36)

 Page 35 / 36

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. $\frac{{72}^{2}}{5}$
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. $N\left(72,\frac{72}{\sqrt{50}}\right)$ 3. Exp (72) 4. $Exp\left(\frac{1}{72}\right)$ 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. $\frac{3}{9}$ 2. $\frac{7}{9}$ 3. $\frac{3}{10}$ 4. $\frac{7}{10}$ 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? 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 $\overline{x}$ 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

for poisson distribution mean............variance.
both are equal to mu
Faizan
mean=variance
Faizan
what is a variable
something that changes
Festus
why we only calculate 4 moment of mean? asked in papers.
why we only 4 moment of mean ? asked in BA exam
Faizan
Good evening, can you please help me by sharing regression and correlation analysis notes....thank you in advance
Hello, can you please share the possible questions that are likely to be examined under the topic: regression and correlation analysis.
Refiloe
for normal distribution mean is 2 & variance is 4 find mu 4?
repeat quastion again
Yusuf
find mu 4. it can be wrong but want to prove how.
Faizan
for a normal distribution if mu 4 is 12 then find mu 3?
Question hi wrong ha
Tahir
ye BA mcqs me aya he teen he. 2dafa aya he
Faizan
if X is normally distributed. (n,b). then its mean deviation is?
Faizan
The answer is zero, because all odd ordered central moments of a normal distribution are Zero.
nikita
which question is zero
Faizan
sorry it is (5,16) in place of (n,b)
Faizan
I got. thanks. it is zero.
Faizan
How did we get the 24000
where do I start
in a large restaurant an average of every 7 customers ask for water with the their meal. A random sample of 12 customers is selected, find the probability that exactly 6 ask for water with their meal
any body with idea
Rufai
conditional probability
Ramesh
can you help please
Rufai
iam really sorry. it's been long since I used these things. I just gave you a hint though
Ramesh
ok
Rufai
this follows binomial distribution. p(X=6)=12C6*(0.6)^6*0.4^6 use this formula n find.
syeda
can you explain the cosidered variable in the formula
Divya
x is variable wich is exactly 6 costumers
syeda
n is number of customers
syeda
ncx*p^X*q^X?
Divya
q^n-x
syeda
oh right !!! thanks yaar
Divya
I agree with Seyda too
Hoshyar
I agree with Syeda too
Hoshyar
7/12 =0.58is it?
yousaf
.
yousaf
r8
khalid
what is descriptive statistic
Descriptive statistics are brief descriptive coefficients that summarize a given data set, which can be either a representation of the entire or a sample of a population. Descriptive statistics are broken down into measures of central tendency and measures of variability (spread).
Divya
are you getting this ?
Divya
if so let me know
Divya
yes m getting
Ramesh
fine
Divya
what's taking place can l join u
Anest
yeah !!why not? sure
Divya
okey thanks
Anest
where are statistics used
hello
Giannis
Hi
Makhosi
how u doing
Muhid
everywhere
Faizan
please guys uses of statistics....
the upper quartile of the population 10,12,14,16,18,20,25,15,11,11,17,is................?
Gach
The probability range is 0 to 1... but why we take it 0 to 1....
because in probability 1 means success and 0 means failure and it cnnt be more or less than 1 and 0.
syeda
b/c v hv mazimum probibliy 1 and minimum which is.no.probiblity is 0.so.v hv the range from 0 to 1
khalid
the size of a set is greeter than its subset
Hoshyar
The probability of an event will not be less than 0.  This is because 0 is impossible (sure that something will not happen).The probability of an event will not be more than 1. This is because 1 is certain that something will happen
Divya
what do they mean in a question when you are asked to find P40 and P88
I dont get your question! What are you talk ING about?
Mani
hi
Mehri
you're asked to find page 40 and page 88 on that particular book.
Joseph
hi
ravi
any suggestions for statistics app better than this
ravi
sorry miss wrote the question
omar
No problem) By the way. I NEED a program For statistical data analysis. Any suggestion?
Mani
Eviews will help u
Hello
Okonkwo
arey there any data analyst and working on sas statistical model building
ravi
Hi guys ,actually I have dicovered that the P40 and P88 means finding the 40th and 88th percentiles 😌..
Megrina
who can explain the euclidian distance
ravi
I am fresh student of statistics (BS) plz guide me best app or best website relative to stat topics
Noman
IMAGESNEWSVIDEOS A Dictionary of Computing. measures of location Quantities that represent the average or typical value of a random variable (compare measures of variation). They are either properties of a probability distribution or computed statistics of a sample. Three important measures are the mean, median, and mode.