Probability and Statistics Questions

Higher Institute of Transport and Logistics (HITL)

Semester: First Semester

Level: 200

Year: 2015

School/Faculty: HITL

DEPARTMENT: LECTURER(S): DR. N. Siri Konje

Academic Year: 2015/2016

COURSE CODE: TL 1106 COURSE TITLE: Probability and Statistics

DATE: 16/05/2015 HALL: PBC (1 & 3) TIME: 08:00 – 11:00

Instructions: Answer all questions

THE UNIVERSITY OF BAMENDA

P.O BOX 39 Bambili

REPUBLIC OF CAMEROON

Peace-Work-Fatherland

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. 17 0

Question 1 (10 points)

A statistics class of 40 students took a quiz. The highest possible scores was 4 points.

Ten students score 4 points, twelve students scored 3 points, eight students 2 points, six

students scored 1 point and four students scored 0. Compute the mean, median, standard

deviation, first quartile and third quartile of the scores.

Question 2 (9 points)

a) Is the sample mean always equal to one of the values in the sample? If so, explain

why. If not, give an example.

b) Find a sample for which the median is always equal to one of the values in the

sample

c) Define the following (i) an event, (ii) a random variable

d) How can random variables be distinguished

Question 3 (8 points)

a) Scores on a standardize test are approximately normally distributed with mean

480 and standard deviation of 90.

i) What proportion of the scores is above 90

ii) What problem of the scores is between 420 and 520?

b) The sample mean and standard deviation of the filled-weight of 100 boxes are

12.05 and 0.1 respectively. Find a 95 percent and 99.7 percent interval for the

mean filled weight of all the boxes.

Question 4 (8 points)

A box contains ten laptops, 3 of which are defective. Two laptops are drawn at random

and tested. Let A be the event that the first laptop drawn is defective and let B be the

event that the second laptop is defective. Find: (i) P(A), (ii) P(A/B), (iii) P(B). Are A and

B independent events? Explain

SUCCESS WISHES!!!

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