An engineer wants to compare the tensile strengths of steel bars that are produced using a conventional method and an experimental method. (The tensile strength of a metal is a measure of its ability to resist tearing when pulled lengthwise.) To do so, the engineer randomly selects steel bars that are manufactured using each method and records the following tensile strengths (in newtons per square millimeter)

Experimental Method

395 389 421 394 407 411 389 402 422 416 402 408 400

386 411 405 389

Conventional Method

362 352 380 382 413 384 400 378 419 379 384 388 372

383

At = 0.10, can the engineer claim that the experimental method produces steel with greater mean tensile strength?Should the engineer recommend using the experimental method? Assume the population variances are not equal. Use the rejection region method.