CSIT 2nd Semester
Statistics I Board Question Paper 2082 Old Course

STA 164-2082 ✡
Tribhuvan University
Institute of Science and Technology
2082
✡
Bachelor Level/First Year/Second Semester/Science
Computer Science Information Technology (STA 164)
(Statistics I)
(Old Course)
Full Marks:60 Pass Marks:24 Time:3 hours

Candidates are required to give their answers in their own words as for as practicable.
The figures in the margin indicate full marks

Section A
Long Answer Questions
Attempt any Two question.
[2x10=20]
1.

What do you understand by measures of central tendency and dispersion in descriptive statistics? The number of sick days due to colds and flu last was recorded of a sample of 12 adults. The data are: 3, 4, 2, 1, 0, 4, 7, 4, 6, 5, 2 and 4. Compute mean, median, mode and standard deviation of above data.

2.

Distinguish between positive and negative correlation? Attempting to analyze the relationship between advertising and sales, the owner of the computer store recorded the monthly advertising budget (in 10000 Rs.) and the sales (in lakh Rs.) for a sample of 5 months. The data are listed here:

Advertising58101215
Sales710131416

a) Compute the correlation coefficient and interpret its value.
b) Find the regression equation of sales on advertising.
c) Estimate the sales when advertising is Rs.100000.

3.

Define Poisson probability distribution? The number of telephone calls received during the month of May is summarized in the following table.

Number of telephone calls per day01234
Number of days92524139

Fit the Poisson distribution.

Section B

Attempt any Eight questions

[8x5=40]
4.

What is sampling? Describe briefly two different methods of sampling.

5.

Define partition values. The following are the marks obtained by 95 students in Statistics.

Marks20-3030-4040-5050-6060-7070-80
No. of students101926158

Find the lowest marks of the top 15% student.

6.

A factory produce two types of electric lamps A and B, in an experiment relating their life, the following results were obtained:

Length of life in hours in 1000 hrs5-77-99-1111-13
Numbers of lamps A3681
Numbers of lamps B4952

Find which lamp is more uniform or consistency with regard to the length of life?

7.

Define probability. A problem is given to three students, A, B and C whose chances of solving the problem are in ratio 2: 3: 5. Find the probability that (i) all of them solve the problem. (ii) none of them solve the problem. (iii) the problem will be solved.

8.

Discuss Binomial probability distribution. If number of trials is 20 and the probability of success is 3/4 of binomial distribution, find mean and variance the distribution. Also, find P(x =2).

9.

What is the conditional probability? The table given below summarizes the results of all the driving test taken at a test centre.

ResultMaleFemaleTotal
Pass433578
Fail81523
Total5150101

A person is chosen at random from the those who took their test. Find the probability that the person (i) passed in the driving test (ii) chosen is female given the person passed the test.

10.

Define random variable. The six faces of a fair cubical dice are numbered 1, 2, 2, 3, 3, and 3. When the dice is thrown once, the score is the number appearing on the top face. This is denoted by X. Find (i) E(X) (ii) E(X�) (iii) V(X).

11.

Let X and Y be random variables with joint density function:
f(x ,y) = kxy , 0=x=1 , 0= y =1
=0 , otherwise .
Find (i) the value of k (ii) E(X)

12.

Define normal distribution. The height of a group twenty-year girls are normally distributed with mean 163.2 cm and standard deviation 4.7 cm. Find the probability that one of these girls will have height more than 168 cm.
OR
Write short note on any two:
(i)Nominal and Ordinal scale
(ii)Snowball sampling
(iii)Five �number Summary.