Question

Data on oxide thickness of semiconductors are as follows: 426 433 414 418 420 437 416 409 432 436 422 426 412 435 434 427 409 426 407 436 422 426 415 416 Consider this data as a sample of the population. (a) Calculate a point estimate of the mean oxide thickness for all wafers in the population. (Round your answer to 3 decimal places.) (b) Calculate a point estimate of the standard deviation of oxide thickness for all wafers in the population. (Round your answer to 2 decimal places.) (c) Calculate the standard error of the point estimate from part (a). (Round your answer to 2 decimal places.) (d) Calculate a point estimate of the median oxide thickness for all wafers in the population. (Express your answer to 1 decimal places.) (e) Calculate a point estimate of the proportion of wafers in the population that have oxide thickness greater than 430 angstrom. (Round your answer to 4 decimal places.) (a) The point estimate of the mean oxide thickness is Angstroms. (b) The point estimate of the standard deviation of oxide thickness is Angstroms. (c) The point estimate of the standard error of the mean is Angstroms. (d) The point estimate of the median oxide thickness is Angstroms. (e) The estimate of the proportion requested is

Answer 1

a.

b.

Create the following table.

data	data-mean	(data - mean)2
426	2.9167	8.50713889
433	9.9167	98.34093889
414	-9.0833	82.50633889
418	-5.0833	25.83993889
420	-3.0833	9.5067388900001
437	13.9167	193.67453889
416	-7.0833	50.17313889
409	-14.0833	198.33933889
432	8.9167	79.50753889
436	12.9167	166.84113889
422	-1.0833	1.17353889
426	2.9167	8.50713889
412	-11.0833	122.83953889
435	11.9167	142.00773889
434	10.9167	119.17433889
427	3.9167	15.34053889
409	-14.0833	198.33933889
426	2.9167	8.50713889
407	-16.0833	258.67253889
436	12.9167	166.84113889
422	-1.0833	1.17353889
426	2.9167	8.50713889
415	-8.0833	65.33973889
416	-7.0833	50.17313889

Find the sum of numbers in the last column to get.

So standard deviation is

c. Standard error is

d. The median is the middle number in a sorted list of numbers. So, to find the median, we need to place the numbers in value order and find the middle number.

Ordering the data from least to greatest, we get:

407   409   409   412   414   415   416   416   418   420   422   422   426   426   426   426   427   432   433   434   435   436   436   437   

As you can see, we do not have just one middle number but we have a pair of middle numbers, so the median is the average of these two numbers:

Median=

e, Ordering the data from least to greatest, we get:

407   409   409   412   414   415   416   416   418   420   422   422   426   426   426   426   427   432   433   434   435   436   436   437   

Hence we see 7 values are greater than 430

So