Question

I understand that these will be considered seperate questions, but could I get a full answer please.

Thank you.

1 A civil engineering agency monitors water quality by measuring the amount of suspended solids in a sample of river water. The following results, measured in parts per million, were observed over 60 days:

21.2 |
19.9 |
20.2 |
15.6 |
17.6 |
14.0 |
19.7 |
18.3 |
26.2 |
23.6 |

20.2 |
19.8 |
22.2 |
27.3 |
23.4 |
19.8 |
22.3 |
16.9 |
16.4 |
22.0 |

19.8 |
21.1 |
20.4 |
18.6 |
21.8 |
22.5 |
20.0 |
21.6 |
26.3 |
22.3 |

25.9 |
21.0 |
19.0 |
23.3 |
26.1 |
22.3 |
23.6 |
20.1 |
22.8 |
17.8 |

12.9 |
25.7 |
26.2 |
25.1 |
22.5 |
22.3 |
21.8 |
22.2 |
22.6 |
17.3 |

22.6 |
20.5 |
20.6 |
24.7 |
22.3 |
21.4 |
25.4 |
17.7 |
18.9 |
21.7 |

(a) Plot a histogram of this data, with classes (12.25, 14.25], (14.25, 16.25], …, either manually or using Excel.

(b) Comment on the shape of the distribution of the amount of suspended solids. What measures of location and spread are appropriate for this data set and why? Calculate them.

(c) Assuming that the data can be sufficiently well modelled by a normal distribution, construct a 95% confidence interval for the mean number of suspended solids.

(d) Is there any evidence, at the 95% confidence level, that the mean number of suspended solids exceeds 25 parts per million?

Answer #1

The Student Government Association is interested in an estimate
of the mean number of hours students work per week. They take a
simple random sample of 89 students. The data they collected can be
found in the column labeled “Number of hours worked per week”. Use
the sample data to construct a 95% confidence interval for the mean
number of hours worked. Write one or two sentences to communicate
to the Student Government Association the estimate and the margin
of...

BODYFAT
HEIGHT
12.9
67.75
6
72.25
25.5
66.25
10.6
72.25
28.1
71.25
20
74.75
19.2
69.75
11.9
72.5
4.3
74
12.9
73.5
7.6
74.5
8.3
76
20.4
69.5
19.8
71.25
22.2
69.5
20.9
66
28
71
23
71
15.6
67.75
16.9
73.5
18.5
68
15.5
69.75
14.7
68.25
18
70
13.6
67.75
4.3
71.5
8
67.5
22.4
67.5
4.4
64.75
8.9
69
13.2
73.75
6.3
71.25
12.6
71.25
21
71
31.9
73.5
39.1
65
23.2
70
26.6
68.25
34.3
72.25...

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