# The times per week a student uses a lab computer are normally

- The Times per week a student uses a lab computer are normally distributed, with a mean of 6.6 hours and a standard deviation of 1.1 hours. A student is randomly selected. Find the following probabilites

a) Find the probability that a student uses a lab computer less than 4 hours per week is

b ) The probabilty that student uses a lab computer between 5 to 7 hours per week is

c) The probability that a student uses a lab computer more than 8 hours per week is

All answers round to 3 decimal places

- A researcher wishes to estimate with 95% confidence. The proportion of adults who have high speed internet. Her estimate must be 1% of the true proportion.

Find the minimum sample size needed using a prior study that found 34% of the respondents saying they have high speed internet. Then find the minimal sample size for no preliminary estimates available - A random sample of forty-two 200-meter swims has a meant time of 3.724 minutes and a standard deviation of 0.080 minutes. A 95% confidence interval for the population mean time is (3.704,3.744)

Construct a 95% confidence interval for the population mean time using a standard deviation of 0.05 minutes. Which confidence interval is wider?

- The state test scores for 12 randomly selected high school seniors are shown below

Assume the population is normally distributed.

1428 1220 990

698 729 831

730 749 546

(a) Find the sample mean

(b) Find the sample standard deviation.

(c) construct a 99% confidence interval for the population mean u

5. Assume the Poison distribution applies use the given mean to find the indicated probability.

Find P(4) when u=8

6..

Find the equation of the regression line for the data. Then construct a scatter plot of the data and draw the regression line. (the pair of variables has a significant correlation) then us the regression equation to predict the value of y for each of the given x-values, if meaningful. The table shoes shoe size and height in inches for 6 men.

** **

Shoe size, x |
Height, y |

6.0 |
65.5 |

10.0 |
70.5 |

11.0 |
72.5 |

11.5 |
74.5 |

12.0 |
74.5 |

13.0 |
72.5 |

What is the regression equation?

Predict the value of y for x = 9.5

Predict the value of y for x = 8.0?

Predict the value of y for x = 14.5?

Predict the value of y for x = 9.0 ?

7. For your study on the food consumption habits of teenage males you randomly select 10 teenage males and aske each how many 12 ounch servings soda he drinks each day. The results are below. At a=0.01, is there enough evidence to support the claim that teenage males drink fewer than three 12ounce servings of soda per day? Assume the population is normally distributed?

3.4 |

2.9 |

2.6 |

2.1 |

1.9 |

3.9 |

2.6 |

3.6 |

3.5 |

1.2 |

Write the claim mathematically and identify Ho and Ha ?

Use technology to find the P-value

Decide whether to reject or fail to reject the null hypothesis?

Interpret the decision in the context of the original claim.

8. An employment information service claims the mean annual pay for the full-time male workers over age 25 without a high school diploma is $22,350. The annual pay for a random sample of 10 full-time workers over age 25 without a high school diploma is listed. At a=0.10, test the claim that the mean salary is $22,350. Assume the population is normally distributed.

20,650 |

21,135 |

22,355 |

21,399 |

22,974 |

16,914 |

19,150 |

23,194 |

24,187 |

26,287 |

Write the claim mathematically and identify Ho and Ha ?

Find the critical value and identify the rejection region?

Find the standardized test statistic.

Decide whether to reject or fail to reject the null hypothesis?

Interpret the decision in the context of the original claim.?

9. A company that makes cola drinks states that the mean caffeine content per 12-ounch bottle of cola is 50milligrams. You want to test this claim. During your test you find that a random sample of thirty 12-ounce bottles of cola has a mean caffeine content of 49.3 milligrams with a standard deviation of 6.6 milligrams. At a=0.02, can you reject the companys claim?

Write the claim mathematically and identify Ho and Ha ?

Find the critical value and identify the rejection region?

Decide whether to reject or fail to reject the null hypothesis?

10. The altitude (in thousands of feet) and speed of a plane(in feet per second) for various altitudes is shown below.

Altitude, x |
Speed, y |

0 |
962.2 |

5 |
1106.8 |

10 |
981.8 |

15 |
1016.8 |

20 |
994.7 |

25 |
1007.8 |

30 |
1033.1 |

35 |
1104.9 |

The correlation is strong or weak AND positive or negative linear correlation?

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