log normal distribution mean

Find the highest control limit for a normally distributed curve with a mean of 20 and a standard deviation of 3. => 23 or 29 or 11 or 26..

What formula is used to gain information about a sample mean when the variable is normally distributed or when the sample size is 30 or more? => z = X - μ σ or z = X ‾ - μ σ n or z = X ‾ - μ σ n or z = X - μ σ..

Let X denote the number of scores on a test. If X is normally distributed with a mean of 90 and a standard deviation of 10, find the probability that X is not less than 70. => 0.4772 or 0.7472 or 0.7972 or 0.9772..

The scores made by candidates in a certain test are normally distributed with mean of 500 and standard deviation of 100. What percentage of candidates received scores between 400 and 700? => 88.15% or 81.85% or 88.51% or 85.81%..

The scores made by candidates in a certain test are normally distributed with mean 500 and standard deviation 100. What is the percentage of candidates who scored less than 400? => 15.87% or 17.85% or 18.57% or 15.78%..

Assume that the weights of 3,000 students at a university are normally distributed with mean 150 pounds and a standard deviation of 7 pounds. If 100 samples of 30 students each are obtained, then what would be the expected mean and standard deviation of the r..

Mr. John gave his students a test in the class. The scores were normally distributed with a mean of 75 and standard deviation of 4. What percent of the students scored between 71 and 79? => 95% or 99.7% or 68% or 34%..

A truck was loaded with sacks of onions whose weights were normally distributed with a mean of 35 lb and a standard deviation of 2 lb. What is the probability that a sack of onions will weigh more than 37 lb? => 0.1857 or 0.3143 or 0.1587 or 0.3413..

Students of a class were given an aptitude test. Their scores were found to be normally distributed with mean 65 and standard deviation 7. What percent of the students scored between in the range 51 - 72? => 47.72% or 81.85% or 34.13% or 13.59%..

The mean lifetime of a clock is 30 months. If the distribution is normal with a standard deviation of 4 months, then for how many months should a guarantee be made if the manufacturer does not want to exchange more than 5% of the clocks? => 23 months or 24 months or 20..