43. Let X have a Standard Normal Distribution. Find P( – 1.27 < X < 2.05). A. 0.8777 В. 0.8977 С. 0.9177 D. 0.9377

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Current Attempt in Progress In the manufacture of electroluminescent lamps, several different layers of ink are deposited onto a plastic substrate. The thickness of these layers is critical if specifications regarding the final color and intensity of light of the lamp are to be met. Let X and Y denote the thickness of two different layers of ink. It is known that X is normally distributed with a mean of 0.1 millimeter and a standard deviation of 0.00031 millimeter, and Y is also normally distributed with a mean of 0.23 millimeter and a standard deviation of 0.00017 millimeter. The value of r for these variables is equal to zero. specifications call for a lamp to have a thickness of the ink corresponding to x in the range of 0.099535 to 0.100465 and Yin the range of 0.22966 to 0.23034 millimeter. What is the probability that a randomly selected lamp will conform to specifications? Round your answer to four decimal places (e.g. 98.7654).

Central High School believes their students have unusually high SAT scores on average. The school has 165 students.Based on national data, the average SAT score is 1067 with a population standard deviation of 207. Assume SAT scores are normally distributed. Let X be the random variable representing the mean SAT scores for groups of 165 randomly selected students.a. Fill in the blank, rounding your answers to 2 decimal places if needed. According to the Central Limit Theorem, X is approximately normal with a mean of  and a standard error of the mean  .b. Find the z-score associated to a sample with a mean of 1109, using the sampling distribution. Round your answer to two decimal places. c. Find the probability that a randomly selected sample of 165 students has a mean SAT score higher than 1109. Round your answer to 4 decimal places. d. Central High School finds that for their students, the average SAT score is 1109. Are they justified in saying their students perform unusually well on…