English translation:
If the quality control manager wants to estimate the average life of lamps with 20 hours, with a confidence level of 95% and an error of 10% is assumed. What is the sample size?
Multiply "7" by each term inside the parentheses.
7(x-20) = 7x-140
answer: 7x-140
1 ) V = 1/3 * 18² * 3.14 * 6 = 2,034.72 mm³
2 ) V = 1/3 * 6² * 3.14 * 9 = 339.12 in³
3 ) V = 1/3 * 150² * 3.14 * 240 = 5,652,000 in³
5,652,000 : 12,000 = 471 weeks
