Question

Data on oxide thickness of semiconductors are as follows: 424 431 414 417 420 434 420 408 430 431 423 426 409 436 435 430 413 426 410 436 422 429 415 414

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.)

Answer 1

Solution: Given that values 424 431 414 417 420 434 420 408 430 431 423 426 409 436 435 430 413 426 410 436 422 429 415 414

(a) Mean = sum of terms/number of terms = 10153/24 = 423.042

(b) Standard deviation = ? = 8.98

(c) Standard error = ?/sqrt(n) = 8.98/sqrt(24) = 1.83

(d) Median = 423.5

Explanation:
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:

408 409 410 413 414 414 415 417 420 420 422 423 424 426 426 429 430 430 431 431 434 435 436 436

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 = (423+424)/2 = 423.5

(e) p = X/n = 6/24 = 0.2500