1420 words - 6 pages

Take- Home 1

Chapters 1-4, 6 & Sect. 7.1-7.2

1. xmin=42; xmax=73; sample distribution; find range, midrange, and approximate standard deviation.

Range=highest value-lowest value

73-42=31

midrange= highest value+lowest value2

73+422=57.5

Approx. standard deviation

s=R4

314=7.75

2. Determine whether it is a parameter or a statistic: explaining answers.

a) 22% United Farm Union members

It is a parameter because the measure was obtained by using all the data values from the United Farm Union member population, which is a specific population.

b) Results of survey by Redbook Magazine – 86%

It is a statistic because ...view middle of the document...

Mode of the raw scores:

Mode is the value that occurs most often

Mode = 10

10. Range of the raw scores

R= Highest value-lowest value

R: 15-6 = 9

11. Class width if you have 5 classes:

width= R# of classes

95=1.8 ≈2

12. Complete table of frequency distribution:

Class | ƒ | cƒ | rƒ | crƒ |

6 – 7 | 4 | 4 | .11 | 11% |

8 – 9 | 8 | 12 | .23 | 34% |

10 – 11 | 10 | 22 | .29 | 63% |

12 – 13 | 7 | 29 | .20 | 83% |

14 – 15 | 6 | 35 | .17 | 100% |

35 1.00

13. 35 students; mean score of sample was 33 and ∑(x-)2 = 800. What was variance and standard distribution of his sample?

Variance= ∑(x-)2 n-1

80035-1=23.53

Standard deviation = √s2

23.53=4.85

14. 250 test scores; Sue’s better than 193 of them; what’s her percentile rank?

Percentile = # of values+0.5total # of values*100%

193+0.5250*100%=77.4%

15. Make frequency distribution; CW = 7; include – class limits, midpoints, frequencies, bounds, relative frequencies, and cumulative frequencies.

Classes | Bounds | Midpoints | Frequency | cƒ | rƒ |

101 – 107 | 100.5 – 107.5 | 104 | 2 | 2 | .08 |

108 – 114 | 107.5 – 114.5 | 111 | 3 | 5 | .12 |

115 – 121 | 114.5 – 121.5 | 118 | 7 | 12 | .28 |

122 – 128 | 121.5 – 128.5 | 125 | 8 | 20 | .32 |

129 – 135 | 128.5 – 135.5 | 132 | 5 | 25 | .20 |

25 1.00

16. Frequency Histogram

17. Display data as box and whisker plot.

18. Display data as stem-and-leaf plot

10 | 1 | 5 | 8 | | | | | | |

11 | 1 | 4 | 5 | 6 | 7 | 8 | 9 | 9 | |

12 | 0 | 3 | 3 | 4 | 5 | 7 | 7 | 8 | 8 |

13 | 1 | 1 | 2 | 4 | 5 | | | | |

19. Display the data as an ogive curve.

20. Corresponding z score for test score of 51 if the = 45 and s = 4?

zscore=x-s

51-454=1.5 →.9332

21. popular standard score – T-score = T= +s(z); what is the T-score if raw test score is 57; mean is 55 and SD is 1.45?

zscore=x-s

57-551.45=1.38 →.9162

55+1.45.9162= 56.33

22. What z-score corresponds with 61.9% of area under curve?

61.9% = .6190 → .3029

23. What is the score (nearest whole #) on a test where you score @ P67 if the test has a mean of 57 and SD of 3.7?

P67 = 67% = .6700 → .44

X=Zσ+μ

(.44)(3.7) + 57 = 58.63 ≈ 59

24. Normal distribution; approximate % of population falls:

a) between ±1= 68%

b) above +1 = 15.86%

c) between ± 2 = 95%

d) below – 2 = 2.27%

e) above Q1 = 75%

f) between Q1 and Q3 = 50%

g) Q1 and 1 = 59%

25. random sample of 210 people; mean height = 68 inches and s = 3.1 inches.

a) Heights at ± 1s?

Mean ± S

68+3.1 = 71.7

68 – 3.1 = 64.9

The heights are 71.7 inches and 64.9 inches.

b) how many people will fall between ± 1s?

68% of 210

210* .68 = 142.8 people

c) how many...

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