Estadistica (Ejercicios Practicos)

17/Sep/2012

Chapter 2: Descriptive Statistics, Tabular and Graphical Presentations
21. The Nielsen Home Technology Report provided information about home technology and its usage. The following data are the hours of personal computer usage during one week for a sample of 50 persons.

a. A frequency distribution (use a class width of three hours)
b. A relative frequency distributionc. Histogram
d. An Ogive
Usage (Hrs) | Frequency | Relative Frequency | Cumulative Frequency |
3.7 | 14 | 0.28 | 0.28 |
6.7 | 23 | 0.46 | 0.74 |
9.7 | 6 | 0.12 | 0.86 |
12.7 | 5 | 0.1 | 0.96 |
15.7 | 2 | 0.04 | 1 |

e. Comment on what the data indicate about personal computer usage at home.
The data depicts that almost 80% of people that spend hours in computer on theirhome, employ between 0.7 to 6.7 hours per week.

26. The American Association of Individual Investors conducts an annual survey of discount brokers. The following prices charged are from a sample of 24 discount brokers (AAII Journal, January 2003). The two types of trades are a broker-assisted trade of 100 shares at $50 per share and an online trade of 500 shares at $50 per share.
Broker |Broker-Assisted 100 Shares at $50/Share | Online
500 Shares at $50/Share | | Broker | Broker-Assisted 100 Shares at $50/Share | Online
500 Shares at $50/Share |
Accutrade | 30.00 | 29.95 | | Merrill Lynch Direct | 50.00 | 29.95 |
Ameritrade | 24.99 | 10.99 | | Muriel Siebert |45.00 | 14.95 |
Banc of America | 54.00 | 24.95 | | NetVest | 24.00 | 14.00 |
Brown & Co. | 17.00 | 5.00 | | Recom Securities | 35.00 | 12.95 |
Charles Schwab | 55.00 | 29.95 | | Scottrade | 17.00| 7.00 |
CyberTrade | 12.95 | 9.95 | | Sloan Securities | 39.95 | 19.95 |
E*TRADE Securities | 49.95 | 14.95 | | Strong Investments | 55.00 | 24.95 |
First Discount | 35.00 | 19.75 | | TD Warehouse |45.00 | 17.95 |
Freedom Investments | 25.00 | 15.00 | | T. Rowe Price | 50.00 | 19.95 |
Harrisdirect | 40.00 | 20.00 | | Vanguard | 48.00 | 20.00 |
Investors national | 39.00 | 62.50 | | Wall Street Discount| 29.95 | 19.95 |
MB Trading | 9.95 | 10.55 | | York Securities | 40.00 | 36.00 |

a. Round the trading prices to the nearest dollar and develop a stem-and-leaf display for 100 shares at $50 per share. Comment on what you learned about broker-assisted trading prices.
1 | 0 3 7 7 | | | | ||
2 | 4 5 5 | The Broker-Assisted trading prices are evenly distributed |
3 | 0 0 5 5 9 | with a little bias to prices higher than $40 per share, also |
4 | 0 0 0 5 5 8 | and average of $36 per share. | | |
5 | 0 0 0 4 5 5 | | | | | |

b. Round the trading prices to the nearest dollar and develop a stretched stem-and-leaf display for 500 shares online at $50 per share.Comment on what you learned about online trading prices.
0 | 5 7 | | | | | |
1 | 0 1 1 3 4 5 5 5 8 | | | | | |
2 | 0 0 0 0 0 0 5 5 | The online trading prices are normally distributed around |
3 | 0 0 0 6 | $20 per share average. | | |
4 | - | | | | | |
5 | - | | | | | |
6 | 3 | | | | | |

34. Table 2.13 provides financial data for a sample of 36...