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1. The rads (radiation dose, Y) were studied as a function of current X1(in mill

ID: 2907289 • Letter: 1

Question

1.       The rads (radiation dose, Y) were studied as a function of current X1(in milliamps) and exposure time X2(in seconds). The data are in the following table (sample size n=40):

Rads

Current

Time

7.4

10

0.25

14.8

10

0.5

29.6

10

1

59.2

10

2

88.8

10

3

296

10

10

444

10

15

592

10

20

11.1

15

0.25

22.2

15

0.5

44.4

15

1

88.8

15

2

133.2

15

3

444

15

10

666

15

15

888

15

20

14.8

20

0.25

29.6

20

0.5

59.2

20

1

118.4

20

2

177.6

20

3

592

20

10

888

20

15

1184

20

20

22.2

30

0.25

44.4

30

0.5

88.8

30

1

177.6

30

2

266.4

30

3

888

30

10

1332

30

15

1776

30

20

29.6

40

0.25

59.2

40

0.5

118.4

40

1

236.8

40

2

355.2

40

3

1184

40

10

1776

40

15

2368

40

20

1.)What is the mean radiations when the current is 15 milliamps and the exposure time is 5 seconds. (Keep 1 decimal place)

2.)The 95% confidence interval for the increase in the mean radiations when the current is fixed and the exposure time change from 5 seconds to 10 seconds is approximately

A. [60.48, 130.80]

B. [12.14, 26.16]

C. [57.46, 78.70]

D. [287.30, 393.50]

Rads

Current

Time

7.4

10

0.25

14.8

10

0.5

29.6

10

1

59.2

10

2

88.8

10

3

296

10

10

444

10

15

592

10

20

11.1

15

0.25

22.2

15

0.5

44.4

15

1

88.8

15

2

133.2

15

3

444

15

10

666

15

15

888

15

20

14.8

20

0.25

29.6

20

0.5

59.2

20

1

118.4

20

2

177.6

20

3

592

20

10

888

20

15

1184

20

20

22.2

30

0.25

44.4

30

0.5

88.8

30

1

177.6

30

2

266.4

30

3

888

30

10

1332

30

15

1776

30

20

29.6

40

0.25

59.2

40

0.5

118.4

40

1

236.8

40

2

355.2

40

3

1184

40

10

1776

40

15

2368

40

20

Explanation / Answer

1.)What is the mean radiations when the current is 15 milliamps and the exposure time is 5 seconds. (Keep 1 decimal place)

Rads=-440.393+19.1475*current+68.08*time

current=15,time=5

Rads=187.22

2) The 95% confidence interval for the increase in the mean radiations when the current is fixed and the exposure time change from 5 seconds to 10 seconds is approximately

C. [57.46, 78.70]

Rads=-440.393+19.1475*current+68.08*time

current=15,time=5

Rads=187.22