# The Standard Normal Distribution - Page 3

Questions

- For normal distribution, what is the probability that an observation is within 1.33 standard deviations from the mean?
- In a standard normal distribution, what is the probability that #P(z<-2.58# OR #z>2.58)#?
- If a woman between the ages 18-24 is randomly selected, what is the probability that her systolic blood pressure is greater than 110?
- In a standard normal distribution, what is the probability that #P(z<.45)#?
- If the variance of the data values in a sample is 225, what is the standard deviation of the data values?
- What is the probability that a data value in a normal distribution is between a z-score of -.18 & 1.23?
- How can I tell if my data is normally distributed? Do the mean, median and mode have to be identical for it to be a normal distribution?
- What is value of #X# such that #P(-X < Z < X)=0.95#?
- Using the standard normal distribution, what is the probability #P(Z=7)#?
- If a set of grades on statistics examination are approximately normally distributed with a mean of 74 and a standard deviation of 7.9, what is the highest B if the top 5% of the students are given A's?
- If a set of grades on statistics examination are approximately normally distributed with a mean of 74 and a standard deviation of 7.9, what is the lowest B if the top 10% of the students are given A's and the next 25% are given B's?
- Let #X# be #N(mu, sigma^2)# so that #P(X<89) = 0.90# and #P(X<94) = 0.95#. How do you find #mu# and #sigma^2#?
- The mean number of seeds in a watermelon is 176 and the standard deviation is 40. What percentage of melons have between 150 and 200 seeds?
- A banker finds that the number of times people use automated-teller machines in a year are normally distributed with a mean of 40.0 and a standard deviation of 11.4. What is the percentage of customers who use them more than 35 times?
- A banker finds that the number of times people use automated-teller machines in a year are normally distributed with a mean of 40.0 and a standard deviation of 11.4. What is the percentage of customers who use them between 45 and 55 times?
- Given the data -6, -9, -6, -4, 10, what is the z-score of 10?
- The mean number of seeds in a watermelon is 176 and the standard deviation is 40. What percentage of melons have less than 100 or greater than 225 seeds?
- What percentage of the population values fall under 1.5 standard deviations in a normal distribution?
- Catfish weights are normally distributed with a mean of 3.2 pounds and a standard deviation of 0.8 pounds. What is the probability that a randomly selected catfish weighs between 3 and 4 pounds?
- The mean score for a standardized test is 1700 points. The results are normally distributed with a standard deviation of 75 points. What is the probability that a student will score more than 1700 points?