# 14.1 Practice final exam 2  (Page 2/2)

If you want to find the probability that the mean of 50 customers is less than $60, the distribution to use is: • $N\left(\mathrm{72},\mathrm{72}\right)$ • $N\left(72,\frac{72}{\sqrt{50}}\right)$ • $\mathrm{Exp}\left(72\right)$ • $\mathrm{Exp}\left(\frac{1}{72}\right)$ B: $N\left(72,\frac{72}{\sqrt{50}}\right)$ The next three questions refer to the following situation: The amount of time it takes a fourth grader to carry out the trash is uniformly distributed in the interval from 1 to 10 minutes. What is the probability that a randomly chosen fourth grader takes more than 7 minutes to take out the trash? • $\frac{3}{9}\text{}$ • $\frac{7}{9}\text{}$ • $\frac{3}{10}\text{}$ • $\frac{7}{10}\text{}$ A: $\frac{3}{9}$ Which graph best shows the probability that a randomly chosen fourth grader takes more than 6 minutes to take out the trash given that he/she has already taken more than 3 minutes? D We should expect a fourth grader to take how many minutes to take out the trash? • 4.5 • 5.5 • 5 • 10 B: 5.5 The next three questions refer to the following situation: 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 5 minutes and a standard deviation of 1.5 minutes. What is the 90th percentile of waiting times (in minutes)? • 1.28 • 90 • 7.47 • 6.92 D: 6.92 The median waiting time (in minutes) for one student is: • 5 • 50 • 2.5 • 1.5 A: 5 Find the probability that the average wait time of 10 students is at most 5.5 minutes. • 0.6301 • 0.8541 • 0.3694 • 0.1459 B: 0.8541 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:

• 16
• 0.2
• 1
• 0.95

B: 0.2

If $P\left(Z<{z}_{\alpha }\right)=0$ . 1587 where $Z$ ~ $N\left(0,1\right)$ , then $\alpha$ is equal to:

• -1
• 0.1587
• 0.8413
• 1

A: -1

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:

• independent groups
• 2 proportions
• matched pairs, dependent groups
• exclusive groups

C: matched pairs, dependent 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

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”?

• Do not reject ${H}_{o}$ . There is insufficient evidence to conclude that there is a difference in the mean scores.
• Do not reject ${H}_{o}$ . There is sufficient evidence to conclude that there is a difference in the mean scores.
• Reject ${H}_{o}$ . There is insufficient evidence to conclude that there is no difference in the mean scores.
• Reject ${H}_{o}$ . There is sufficient evidence to conclude that there is a difference in the mean scores.

D: Reject ${H}_{o}$ . There is sufficient evidence to conclude that there is a difference in the mean scores.

In a survey of 80 males, 45 had played an organized sport growing up. Of the 70 females surveyed, 25 had played an organized sport growing up. We are interested in whether the proportion for males is higher than the proportion for females. The correct conclusion is:

• There is insufficient information to conclude that the proportion for males is the same as the proportion for females.
• There is insufficient information to conclude that the proportion for males is not the same as the proportion for females.
• There is sufficient evidence to conclude that the proportion for males is higher than the proportion for females.
• Not enough information to determine.

C: There is sufficient evidence to conclude that the proportion for males is higher than the proportion for females.

Note: Chi-Square Test of a Single Variance; Not all classes cover this topic. From past experience, a statistics teacher has found that the average score on a midterm is 81 with a standard deviation of 5.2. This term, a class of 49 students had a standard deviation of 5 on the midterm. Do the data indicate that we should reject the teacher’s claim that the standard deviation is 5.2? Use $\alpha =0.05$ .

• Yes
• No
• Not enough information given to solve the problem

B: No

Note: F Distribution Test of ANOVA; Not all classes cover this topic. Three loading machines are being compared. Ten samples were taken for each machine. Machine I took an average of 31 minutes to load packages with a standard deviation of 2 minutes. Machine II took an average of 28 minutes to load packages with a standard deviation of 1.5 minutes. Machine III took an average of 29 minutes to load packages with a standard deviation of 1 minute. Find the $\text{p-value}$ when testing that the average loading times are the same.

• the $\text{p–value}$ is close to 0
• $\text{p–value}$ is close to 1
• Not enough information given to solve the problem

B: p-value is close to 1.

The next three questions refer to the following situation:

A corporation has offices in different parts of the country. It has gathered the following information concerning the number of bathrooms and the number of employees at seven sites:

 Number of employees x 650 730 810 900 102 107 1150 Number of bathrooms y 40 50 54 61 82 110 121

Is the correlation between the number of employees and the number of bathrooms significant?

• Yes
• No
• Not enough information to answer question

B: No

The linear regression equation is:

• $\stackrel{̂}{y}=0.0094-79.96x$
• $\stackrel{̂}{y}=79.96+0.0094x$
• $\stackrel{̂}{y}=79.96-0.0094x$
• $\stackrel{̂}{y}=-0.0094+79.96x$

C: $\stackrel{̂}{y}=79.96x-0.0094$

If a site has 1150 employees, approximately how many bathrooms should it have?

• 69
• 91
• 91,954
• We should not be estimating here.

D: We should not be estimating here.

Note: Chi-Square Test of a Single Variance; Not all classes cover this topic. Suppose that a sample of size 10 was collected, with $\overline{x}$ = 4.4 and $s$ = 1.4 .

${H}_{o}$ : ${\sigma }^{2}$ = 1.6 vs. ${H}_{a}$ : ${\sigma }^{2}$ ≠ 1.6. Which graph best describes the results of the test?

A

64 backpackers were asked the number of days their latest backpacking trip was. The number of days is given in the table below:

 # of days 1 2 3 4 5 6 7 8 Frequency 5 9 6 12 7 10 5 10

Conduct an appropriate test to determine if the distribution is uniform.

• The $\text{p–value}$ is>0.10. There is insufficient information to conclude that the distribution is not uniform.
• The $\text{p–value}$ is<0.01. There is sufficient information to conclude the distribution is not uniform.
• The $\text{p–value}$ is between 0.01 and 0.10, but without alpha (α) there is not enough information
• There is no such test that can be conducted.

A: The $\text{p–value}$ is>0.10. There is insufficient information to conclude that the distribution is not uniform.

­Note: F Distribution test of One-Way ANOVA; Not all classes cover this topic. Which of the following statements is true when using one-way ANOVA?

• The populations from which the samples are selected have different distributions.
• The sample sizes are large.
• The test is to determine if the different groups have the same means.
• There is a correlation between the factors of the experiment.

C: The test is to determine if the different groups have the same means.

Is there any normative that regulates the use of silver nanoparticles?
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
why we need to study biomolecules, molecular biology in nanotechnology?
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
why?
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
what does nano mean?
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
absolutely yes
Daniel
how to know photocatalytic properties of tio2 nanoparticles...what to do now
it is a goid question and i want to know the answer as well
Maciej
Abigail
for teaching engĺish at school how nano technology help us
Anassong
Do somebody tell me a best nano engineering book for beginners?
there is no specific books for beginners but there is book called principle of nanotechnology
NANO
what is fullerene does it is used to make bukky balls
are you nano engineer ?
s.
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
Tarell
what is the actual application of fullerenes nowadays?
Damian
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
Tarell
what is the Synthesis, properties,and applications of carbon nano chemistry
Mostly, they use nano carbon for electronics and for materials to be strengthened.
Virgil
is Bucky paper clear?
CYNTHIA
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
NANO
so some one know about replacing silicon atom with phosphorous in semiconductors device?
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Harper
Do you know which machine is used to that process?
s.
how to fabricate graphene ink ?
for screen printed electrodes ?
SUYASH
What is lattice structure?
of graphene you mean?
Ebrahim
or in general
Ebrahim
in general
s.
Graphene has a hexagonal structure
tahir
On having this app for quite a bit time, Haven't realised there's a chat room in it.
Cied
what is biological synthesis of nanoparticles
how did you get the value of 2000N.What calculations are needed to arrive at it
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1 It is estimated that 30% of all drivers have some kind of medical aid in South Africa. What is the probability that in a sample of 10 drivers: 3.1.1 Exactly 4 will have a medical aid. (8) 3.1.2 At least 2 will have a medical aid. (8) 3.1.3 More than 9 will have a medical aid.