Int.
to Proba & statistics Test-2 MAY , 2019 Time allowed 1:10 Hrs
PLANT SCIENCE 1st Year Students HAWASSA UNIVERSITY
Name: _______________________ ID No. ___________________Section ______________
Max. load 20%
I. Attempt all the following Workout Questions and show all the necessary steps
1. The mean salary paid to 1000 employees of an establishment was found to be 180.4.
Later on after disbursement of the salary it was discovered that the salary of two
employees was wrongly entered as 297 and 165. Their correct salaries were 197 and 185.
Find the correct average salary of the employee. (3 point)
2. A teacher attaches 2 to Quiz, 3 to Mid-term and 5 for Final exam. If a student gets 90, 50
and 60 for Quiz, Mid-term and Final-exam respectively, what is his/her average academic
performance? (2 point)
3. An incomplete frequency distribution is given as follows: (Each 2 point)
Variable 10– 20 20-30 30-40 40- 50- 60-70 60- 70-80 Total
50 60 70
Frequency 1 30 x 65 y 30 25 18 238
2
LCF
Given the median value to be 46, determine the missing frequencies.
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4. Calculate the mean deviation about the mean and median and the mode for the students
score in a test: 7, 10. ,7, 9,7. (Each 1 point)
5. In a certain factory that has a total of 12 workers, the average net salary of a worker was
623 birrs. After a year, the net salary of one of the workers has increased from 654 birr to
680 birr, that of another worker has become 570 birr in place of 595 birr and one of the
workers who had a net salary of 468 birr had left the factory. Compute the new average
net salary of the workers. (4 point)
6. Last semester, the students of Plant science and Horticulture took Stat 1041 course. At
the end of the semester, the following information was recorded. (Each 2 point)
Department Plant science. Horticulture
Mean score 80 65
Standard deviation 25 10
student score mark (X) 85 70
a. Compare the relative dispersions of the two departments’ scores using the appropriate way and
interpret the results
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Interpretation:
b. Which dep’t student performs well?
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