Question

0.In a normal distribution, plus and minus 2 standard deviations from the mean will include about what percent of the observations? A) 50% B) 99.7% C) 95% D)68% 21. What is the area under the normal curve between z -0.0 and z-2.0 A) 1.0000 B) 0.7408 C) 0.1359 D) 0.4770 22. Which of the following is NOT a characteristic of the normal probability distribution? A) Positively-skewed B) Bell-shaped C) Symmetrical D) Mean Mode and median are all equal 23. A new extended-life light bulb has an average service life of 750 hours, with a deviation of 50 hours. If the service life of these light bulbs approximates a no about what percent of the distribution will be between 750 hours and 800 hours? rmal distribution A) 95% B) 68% C) 34% D) 99.7% 24. The mean of a normal distribution is 400 pounds. The standard deviation is 10 pounds. What is the area between 420 pounds and the mean of 400 pounds? A) 0.5000 B) 0.1932 C) 0.4772 D) 0.3413 25. Which of the following is true in a normal distribution? A) Mean equals the mode and the median B) Mode equals the median C) Mean divides the distribution into two equal parts D) All of the above are correct 26. The mean of a normal probability distribution is 500 and the standard deviation is 10. About 95 percent of the observations lie between what two values? A) 475 and 525 B) 480 and 520 C) 400 and 600 D) 350 and 65

Answer 1

20) Area between two standard deviation is 95.45%

So option is C)

21) area between 0 and 2

It is 0.4770

So option D) is correct.

22)

Normal distribution is not positively skewed.

So option A) is correct.