Practice 20 questions on BS-2 - PROBABILITY AND STATISTICS at National Examinations. Free AI-generated quiz on uNotes — track your score, retake anytime.
1A normally distributed random variable X, representing the life of tires, has a mean of 175,000 km and a standard deviation of 20,000 km. What is the probability that a randomly selected tire lasts less than 190,000 km? Which of the following statements correctly describes the probability density function (PDF) of X?
2For the random variable X (tire life) with mean 175,000 km and standard deviation 20,000 km, consider the average life M of a random sample of four tires. Which of the following statements about the probability distribution of M are correct?
3A city-wide survey found that 60% of adult inhabitants favor extending subway lines. If a random sample of 15 adult inhabitants is taken, which of the following probabilities are correctly calculated or represent valid interpretations?
4The number of buses needing maintenance daily follows a Poisson law with an average of four per day. Which of the following statements correctly apply to this scenario?
5The probability density function of a random variable Y is given by $f(y) = K/y^2$ for $1 < y$. Which of the following statements about Y are correct?
6For 21 measurements of Young's modulus, $\Sigma x = 630.0$ and $\Sigma x^2 = 18,980.0$. Assuming X is normally distributed, which of the following statements about confidence limits and hypothesis testing are correct?
7A sample of 900 users of a drill/driver kit showed a mean useful life of 1,280 hours and a standard deviation of 150 hours. Assuming normal distribution of useful life L, which of the following are correct for hypothesis testing and confidence intervals regarding the lifetime?
8In a survey, 1,600 out of 2,000 citizens were satisfied with recycling services. Which of the following statements related to hypothesis testing and sample size determination are correct?
9Steel is manufactured using two processes, A and B. For Process A, $n_A = 10$, $\bar{x}_A = 80.1$, $s_A = 0.9$. For Process B, $n_B = 9$, $\bar{x}_B = 79.8$, $s_B = 1.1$. Which of the following statements are correct regarding hypothesis testing for these processes?
10For a study on residence area (X) and annual electric consumption (Y), with $n=21$, $\sum X_i = 588.0$, $\sum X_i^2 = 16,544.0$, $\sum Y_i = 168.0$, $\sum Y_i^2 = 1,357.0$, $\sum X_i Y_i = 4,731.0$. Which of the following are correct calculations or concepts?
