## Tribhuvan University | Faculty of Management

Office of Dean | Year: 2015

BBA / BIM / BBM / Third Semester / STT 201: Business Statistics

Full Marks: 36 | Pass marks: 2 hrs

Candidates are required to answer all the questions in their own words as far as practicable. The figures in the margin indicate full marks.

** Group “A” – Brief Answer Questions: [4 X 2 = 8]**

1. In a sample of 800 listeners of a FM, 240 listeners like Folk songs. Find 95% confidence internal for a percentage of all listeners.

2. What is sampling? Describe various techniques of sampling.

3. Consignments of 50 calculators contain 8 detective calculators. Two calculators are taken at random from the consignment without replacement what is the probability that:

a. Both are defective

b. Both are not defective

4. A random variable x has the following probability distribution.

X: | 0 | 1 | 2 | 3 | 4 | 5 |

F (x): | 0.20 | 0.25 | 0.10 | 0.15 | 0.20 | 0.10 |

Find the variance

**Group “B” – Short Answer Questions: [4 X 3 = 12]**

5. Sample of 50 mobiles of two brands Samsung and color are taken and average running life (years) of each recorded as shown below:

Samsung | Colors | |

Average life in Years | 11 | 12 |

Standard deviation | 5 | 6 |

Which of the two brands show greater uniformity in life?

6. The average marks of 60 BIM students in English was found to be 64 with standard deviation 5 and the average marks of 60 students of BBM in English was found to be 62 with standard deviation 4. Would you conclude that the marks of the BIM students is more than the marks of BBM students (use p value approach).

7. The marks distribution of 500 students of a certain college are as follows:

Marks: | 0-20 | 20-40 | 40-60 | 60-80 | 80-100 |

No of students: | 40 | 110 | 180 | 120 | 50 |

College Management has decided to give scholarship to top 30% students. How many students will get the scholarship?

8. The TV monitors produced by a certain factory were checked by examining samples of 5. The following table shows the distribution of 120 samples according to the number of defective monitors.

No of defective in a samples of 5ks: | 0 | 1 | 2 | 3 | 4 | 5 | Total |

No of samples | 13 | 19 | 35 | 30 | 15 | 8 | 120 |

Fit the Binomial distribution and find the expected frequencies if the probability of monitor is 0.5

**Group ‘C” – Comprehensive Answer Questions: [2 X 8 = 16]**

9. The normal weight of baby during first six month of life is given in the following.

Age (Months) | 2 | 3 | 4 | 5 | 6 |

Weight (kgs) | 3 | 5 | 8 | 11 | 12 |

a. Estimated the weight of baby of age 1 year.

b. Find the correlation coefficient between age and weight.

10. Construct a Stem and Leaf display for the following data of weight in grams of apples.

63 | 66 | 43 | 80 | 72 | 93 | 65 | 45 | 74 | 50 |

82 | 55 | 73 | 76 | 88 | 68 | 62 | 67 | 92 | 56 |

54 | 53 | 79 | 63 | 47 | 42 | 51 | 62 | 75 | 84 |

Test the normality of the distribution and comment.

## One Comment

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