خلونا نتساعد في ماده احصاء اعمال

[a.5]

independent يختبر m1 مع m2

يعني هذي لازم يكون فيها انتييين (n ) نفس الحكاية قانونها صــ 389 مو اول واحد ثاني واحد

الي تحت الجدول مباشرة هذا جزء من الرئيسي

هذي بالنسبة لزد المحسوبة اما الجدوليــــة
اش تسوي تقولي n1+n2-2 والي يطلع تدوري عليه في الجدول مع الالفه طبعن


كلهم نفس الحكاية بس كل واحد لو قانونه ...


وبالتوفيييييييييييييق ياربــ

ادعولي حبايبــــي

*_*

[Aso0o0om]

بنات لو سمحتوا احد يشرح لي متى احط انه فرض العدم < او > او =
يعني على حسب ايش انا دخت

[•♥fŗŌồtą]

بنات حاولت احل الاسئله الي حطتها جوري صراحه ما عرفت مدري احسها معقده والكتاب مافيه امثله توضح مره

ياليت الي عرفت كيف تحلها تحط لنا الطريقه ^^

[دوده يناسو]

طيب كيف افرق بين الان دبندنت والاس بولد
لانو اثنينهم سيجما ان نون ؟؟

[My World]

يابنات ركزوا شوي ترا شرح البنات وااضح مرة وسهل حاولوا تفصلون القوانين حسب اقسامها
بعدين طبقوا علية بالامثلة وحلوا على فكرة الاسئلة اللي باللون الازرق لانها بصراحه ساعدتني وعرفت كيف صيغه الاسئلة وكيف احل المسالة بترتيب وتلقون حلها اخر كل شبتر
وبالتوفييق يابناااااااااااااااااااااااات
ان شاء الله يكون سهل علينا

[My World]

يابنات خلونا نحل هذي الاسئلة وخاصة اللي فيها الاحتمال ماعرفت احلها

Chapter 8
Sampling Methods and the Central Limit Theorem
41. An experiment involves selecting a random sample of 256 middle managers at random for study.
The sample mean of the annual income is computed to be $35,420 and the sample standard deviation is
$2,050. What is the standard error of the mean?
A) $128.125
B) $138.36
C) $2,050
D) $8.01
Answer: A
43. Suppose a research firm conducted a survey to determine the average amount of money steady
smokers spend on cigarettes during a week. A sample of 100 steady smokers revealed that the sample
mean is $20 and the sample standard deviation is $5. What is the probability that a sample of 100 steady
smokers spend between $19 and $21?
A) 0.4772
B) 0.0228
C) 0.9544
D) $20
Answer: C
44. A state highway inspector needs an estimate of the mean weight of trucks. He selects a random
sample of 49 trucks passing the weighing station and finds the mean is 15.8 tons, with a standard
deviation of the sample of 4.2 tons. What is probability that a truck will weigh less than 14.3 tons?
A) 0.0062
B) 0.3632
C) 0.1368
D) 0.4938
Answer: A
Multiple Choice
Use the following to answer questions 68-71:
An accounting firm is planning for the next tax preparation season. From last year's returns, the firm
collects a systematic random sample of 100 filings. The 100 filings showed an average preparation time
of 90 minutes with a standard deviation of 140 minutes.
69. What is the standard error of the mean?
A) 14 minutes
B) 140 minutes
C) 1.4 minutes
D) 90 minutes
Answer: A
70. What is the probability that the mean completion time will be more than 120 minutes?
A) Approximately zero
B) 0.0832
C) 0.4168
D) 0.0162
Answer: D
Statistical Techniques in Business & Economics, Lind/Marchal/Wathen, 13/e 125
71. What is the probability that the mean completion time is between 1 and 2 hours, i.e., 60 and 120
minutes?
A) Approximately 1.
B) 0.1664
C) 0.8336
D) 0.9676
Answer: D
Use the following to answer questions 72-75:
A group of statistics students decided to conduct a survey at their university to find the average (mean)
amount of time students spend studying per week. Based on a simple random sample, they surveyed 144
students. The statistics showed that students studied an average of 20 hours per week with a standard
deviation of 10 hours.
73. What is the probability that a sample mean would exceed 20 hours per week?
A) 1.0
B) 0.5
C) 1.96
D) Cannot be calculated based on the given information.
Answer:
74. What is the probability of finding a sample mean less than 18 hours?
A) 0.4820
B) 0.4920
C) 0.0080
D) 0.0180
Answer: C
75. What is the probability that average student study time is between 18 and 22 hours?
A) 0.9640
B) 0.0160
C) 0.0360
D) 0.9840
Answer: D
Use the following to answer questions 76-79:
The Intelligence Quotient (IQ) test scores are normally distributed with a mean of 100 and a standard
deviation of 15.
78. You enrolled in a class of 25 students. What is the probability that the class' average IQ exceeds
130?
A) 0.0228
B) 0.9772
C) Approximately zero
D) 0.9544
Answer: C
Use the following to answer questions 80-83:
Truck tire life is normally distributed with a mean of 60,000 miles and a standard deviation of 4,000
miles.
126 Test Bank, Chapter 8
80. What is the probability that a tire will last 72,000 miles or more?
A) 0.0013
B) 0.9987
C) 0.4987
D) 0.9544
Answer: A
81. What is the probability that a tire lasts between 54,000 and 66,000 miles?
A) 0.4332
B) 0.8664
C) 1.00
D) very likely
Answer: B
82. You bought four tires. What is the probability that the average mileage of the four tires exceeds
66,000 miles?
A) 0.0013
B) 0.9987
C) 0.4987
D) 0.9544
Answer: A
83. For a set of four tires, what is the probability that the average tire life is between 57,000 and 63,000
miles?
A) 0.4332
B) 0.8664
C) 1.00
D) very likely
Answer: B

[girl.k.s.a]

السؤال الأول جوآبه a

القانون صـ 277

تآخدي السقمه الي هيا 2,050 وتقسميها على جذر 256

يطلع الناتج الأول 0.128125 طبعا ما عليكي في الصفر الأول

إيش دآ والله صعب مو زي أسئلة كتابنا مافيها probability ولا فيها less than

ولا more than

[•♥fŗŌồtą]

تسلمي ياحلى قيرل :>

اراجع 11 على بال ما تخلصي ^^

[•♥fŗŌồtą]

بنات حابه اتاكد صفحه 376 + 377 + 378 معانا ولا لا ؟!؟

[وردي أحمر]

اللي أعرفه انو معنا

بنات متأكدين ان شابتر 10 مو معنا؟؟؟