c) For the normal distribution of burning times of electric light bulbs, with a mean equal to 1200 hours and a standard deviation equal to 120 hours, what burning time is identified with the (a) upper 50 percent? (b) lower 75 percent? (c) lower 1 percent? (d) middle 90 percent?

If a set of observations is normally distributed, what percent of these differ from the mean by (a) more than 2.50? (b) less than 0.640?

Find out mean deviation from mean by applying direct method from the following distribution: Values: 48, 50, 46, 44, 40, 42, 35, 30, 20, 15.

About what percent of x values lie between the second and third standard deviation (both sides)?

Suppose the exam average in a class is 82% with a standard deviation of 6. What proportion of students scored below 88%? Round to two places.

1) After 5 pts were added to every score in a sample the mean is found to be 62 and the standard deviation is 12. What were the values for the mean and SD before the change? Explain

The mean score for first exam in your first organic chemistry class (section A) was 60, with a standard deviation of 5. Your score on the exam was 70. A. How many standard deviations above the mean is your score?

The scores for a standardized test follow a normal distribution with a mean test score x¯=84, and standard deviationσ=6. What percent of students score below 87? What percent of students score above 95? What percent of students score between 70 and 90? What percent of students score between 95 and 100? What score must a student get higher than to be in the top 10%?

The amount of growth, in a 15-day period, for a population of sunflower plants was found to follow a nor-mal distribution with mean 3.18 cm and standard devia-tion 0.53 cm.9 What percentage of plants grow (a) 4 cm or more?(b) 3 cm or less?(c) between 2.5 and 3.5 cm?