Question

Traffic congestion seems to worsen each year. This raises the question, How much does roadway congestion cost the United States annually? The Federal Highway Administration's Highway Performance Monitoring System conducts an analysis to produce an estimate of the total cost. Drivers in the 73 most congested areas in the United States were sampled, and each driver's congestion cost in time and gasoline was recorded. The total number of drivers in these 73 areas was 128,000,000.

a. Estimate with 95% confidence the total cost of congestion in the 73 areas. (Adapted from the Statistical Abstract of the United States, 2006, Table 1082.)

b. If an organization claims that the total cost of congestion in the 73 areas is greater than $420, do you agree with it based on this sample result?

c. If an organization claims that the total cost of congestion in the 73 areas is less than $450, do you accept it based on this sample result?

Cost ($) 749 381 461 247 252 501 653 507 293 534 308 669 257 375 327 377 301 604 372 237 558 242 382 392 562 557 356 250 314 575 509 456 261 455 328 527 483 508 483 331 402 253 371 587 526 297 455 260 470 749 443 746 314 186 418 280 648 411 509 434 326 420 439 489 465 556 224 336 364 485 409 314 384 262 321 474 393 354 430 615 331 384 510 491 545 527 490 473 447 229 280 538 577 351 266 511 495 532 756 394 364 332 444 302 614 354 314 327 517 252 204 556 410 517 541 439 246 79 575 444 269 451 331 531 227 379 382 411 439 676 330 504 332 493 498 349 415 343 489 331 459 436 482 443 462 480 485 284 380 412 355 441 473 599 374 537 356 585 414 293 760 362 372 497 356 454 422 443 445 310 230 586 401 354 381 322

Answer 1

a. Estimate with 95% confidence the total cost of congestion in the 73 areas.

Step 1 : find the mean, standard deviation and total counts as shown below using excel.

Step 2. : Find the 95% confidence interval .

b. If an organization claims that the total cost of congestion in the 73 areas is greater than $420, do you agree with it based on this sample result?

Hence there is no sufficient evidence to support the claim that the total cost of congestion in the 73 areas is greater than $420

c. If an organization claims that the total cost of congestion in the 73 areas is less than $450, do you accept it based on this sample result?

Hence there is sufficient evidence to claims that the total cost of congestion in the 73 areas is less than $450