Applied Statistics and Probability for Engineers

6-24. An important quality characteristic of water is the con-

centration of suspended solid material. Following are 60 meas-

urements on suspended solids from a certain lake. Construct a

stem-and-leaf diagram for this data and comment on any im-

portant features that you notice. Compute the sample mean,

sample standard deviation, and the sample median.

6-25. The United States Golf Association tests golf balls to

ensure that they conform to the rules of golf. Balls are tested for

weight, diameter, roundness, and overall distance. The overall

202 CHAPTER 6 RANDOM SAMPLING AND DATA DESCRIPTION

6-18. Find the median and the quartiles for the motor fuel

octane data in Exercise 6-14.

6-19. Find the median and the quartiles for the failure data

in Exercise 6-15.

6-20. Find the median, mode, and sample average of the

data in Exercise 6-16. Explain how these three measures of

location describe different features in the data.

6-21. Find the median and the quartiles for the yield data in

Exercise 6-19.

6-22. The female students in an undergraduate engineering

core course at ASU self-reported their heights to the nearest

inch. The data are

62 64 66 67 65 68 61 65 67 65 64 63 67

68 64 66 68 69 65 67 62 66 68 67 66 65

69 65 70 65 67 68 65 63 64 67 67

(a) Calculate the sample mean and standard deviation of

height.

(b) Construct a stem-and-leaf diagram for the height data and

comment on any important features that you notice.

(c) What is the median height of this group of female engi-

neering students?

6-23. The shear strengths of 100 spot welds in a titanium

alloy follow. Construct a stem-and-leaf diagram for the weld

strength data and comment on any important features that you

notice.

5408 5431 5475 5442 5376 5388 5459 5422 5416 5435

5420 5429 5401 5446 5487 5416 5382 5357 5388 5457

5407 5469 5416 5377 5454 5375 5409 5459 5445 5429

5463 5408 5481 5453 5422 5354 5421 5406 5444 5466

5399 5391 5477 5447 5329 5473 5423 5441 5412 5384

5445 5436 5454 5453 5428 5418 5465 5427 5421 5396

5381 5425 5388 5388 5378 5481 5387 5440 5482 5406

5401 5411 5399 5431 5440 5413 5406 5342 5452 5420

5458 5485 5431 5416 5431 5390 5399 5435 5387 5462

5383 5401 5407 5385 5440 5422 5448 5366 5430 5418

42.4 65.7 29.8 58.7 52.1 55.8 57.0 68.7 67.3 67.3

54.3 54.0 73.1 81.3 59.9 56.9 62.2 69.9 66.9 59.0

56.3 43.3 57.4 45.3 80.1 49.7 42.8 42.4 59.6 65.8

61.4 64.0 64.2 72.6 72.5 46.1 53.1 56.1 67.2 70.7

42.6 77.4 54.7 57.1 77.3 39.3 76.4 59.3 51.1 73.8

61.4 73.1 77.3 48.5 89.8 50.7 52.0 59.6 66.1 31.6

261.3

258.1

254.2

257.7

237.9

255.8

241.4

244.3

241.2

254.4

256.8

255.3

255.0

259.4

270.5

270.7

272.6

274.0

260.7

260.6

272.2

251.1

232.1

273.0

266.6

273.2

265.7

255.1

233.7

253.7

264.5

245.5

280.3

248.3

267.0

271.5

240.8

250.2

251.4

270.6

268.9

263.5

262.2

244.8

279.6

272.7

278.7

273.4

242.9

276.6

255.8

276.1

274.2

267.4

244.5

252.0

264.0

237.8

261.0

236.0

247.7

273.6

264.5

285.3

277.8

261.4

253.6

251.8

280.3

268.3

278.5

260.0

271.2

254.8

256.1

264.5

255.4

266.8

254.5

234.3

259.5

274.9

272.1

273.3

279.3

279.8

272.8

251.6

226.8

240.5

268.5

283.7

263.2

257.5

233.7

260.2

263.7

252.1

245.6

270.5

6-26. A semiconductor manufacturer produces devices used

as central processing units in personal computers. The speed of

the device (in megahertz) is important because it determines the

price that the manufacturer can charge for the devices. The fol-

lowing table contains measurements on 120 devices. Construct a

stem-and-leaf diagram for this data and comment on any impor-

tant features that you notice. Compute the sample mean, sample

standard deviation, and the sample median. What percentage of

the devices has a speed exceeding 700 megahertz?

680 669 719 699 670 710 722 663 658 634 720 690

677 669 700 718 690 681 702 696 692 690 694 660

649 675 701 721 683 735 688 763 672 698 659 704

681 679 691 683 705 746 706 649 668 672 690 724

652 720 660 695 701 724 668 698 668 660 680 739

717 727 653 637 660 693 679 682 724 642 704 695

704 652 664 702 661 720 695 670 656 718 660 648

683 723 710 680 684 705 681 748 697 703 660 722

662 644 683 695 678 674 656 667 683 691 680 685

681 715 665 676 665 675 655 659 720 675 697 663

6-27. A group of wine enthusiasts taste-tested a pinot noir

wine from Oregon. The evaluation was to grade the wine on a

0 to 100 point scale. The results follow:

distance test is conducted by hitting balls with a driver swung

by a mechanical device nicknamed “Iron Byron” after the

legendary great Byron Nelson, whose swing the machine is said

to emulate. Following are 100 distances (in yards) achieved by

a particular brand of golf ball in the overall distance test.

Construct a stem-and-leaf diagram for this data and comment

on any important features that you notice. Compute the sample

mean, sample standard deviation, and the sample median.

94 90 92 91 91 86 89 91 91 90

90 93 87 90 91 92 89 86 89 90

88 95 91 88 89 92 87 89 95 92

85 91 85 89 88 84 85 90 90 83

(a) Construct a stem-and-leaf diagram for this data and com-

ment on any important features that you notice.

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