# Stitistical Inference all previous/ past papers

## Stitistical Inference Final paper in 2019

**Question 1**

(a) Differentiate between parametric and non parametric tests? Why non parametric test are used widely? (3+2)

(b) Give short answers (2X3)

- Explain method of least square
- Differentiate between cyclical trend and irregular trend
- Differentiate between regression and correlation

**Question 2**

(a) A travel agency has kept the record of the number of holidays booked and the number of complaints received over the past eight years. The data is as follows: (10)

Year | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 |

Number of holidays booked (x) | 246 | 192 | 221 | 385 | 416 | 279 | 343 | 582 |

Number of complaints received (y) | 94 | 80 | 106 | 183 | 225 | 162 | 191 | 252 |

Construct freehand curve and calculate semi average method and three year moving average

(b) The following are the number of hours which 10 students studied for an examination and the scores they obtained:

Number of Hours Studied | 8 | 5 | 11 | 13 | 10 | 6 | 14 | 15 | 2 | 9 |

Score | 56 | 44 | 79 | 72 | 70 | 54 | 94 | 85 | 33 | 65 |

Calculate Spearman’s Rank Correlation coefficient. (7)

(c) A company has the following data on its sales during the last year in each of its regions and the corresponding number of salespersons employed during this time: (12)

Region | A | B | C | D | E | F |

Sales(units) | 236 | 324 | 298 | 250 | 246 | 202 |

Salespersons | 11 | 12 | 18 | 15 | 13 | 10 |

- Draw a scatter diagram.
- Find the equation of regression line between Sales and Salespersons?
- Estimate sales if salespersons are 14

**Question 3**

Find correlation coefficient and coefficient of determination the marks of 10 students in mathematics and statistics. (10)

Marks in statistics | 42 | 44 | 48 | 42 | 32 | 32 | 44 | 44 | 48 | 35 |

Marks in mathematics | 39 | 47 | 39 | 45 | 28 | 39 | 43 | 29 | 43 | 29 |