Purchase Solution

Standard normal distribution and empirical rule

Not what you're looking for?

Ask Custom Question

Probability, Sampling Distributions, and Inference

1) If light bulbs have lives that are normally distributed with a mean of 2500 hours and a standard deviation of 500 hours, what percentage of light bulbs have a life less than 2500 hours?

2) The lifetimes of light bulbs of a particular type are normally distributed with a mean of 370 hours and a standard deviation of 5 hours. What percentage of bulbs has lifetimes that lie within 1 standard deviation of the mean on either side?

3) The amount of Jen's monthly phone bill is normally distributed with a mean of $60 and a standard deviation of $12. Fill in the blanks:
68% of her phone bills are between $______________ and $______________.

4) The amount of Jen's monthly phone bill is normally distributed with a mean of $50 and a standard deviation of $10. Find the 25th percentile.

5) The diameters of bolts produced by a certain machine are normally distributed with a mean of 0.30 inches and a standard deviation of 0.01 inches. What percentage of bolts will have a diameter greater than 0.32 inches?

6) The annual precipitation amounts in a certain mountain range are normally distributed with a mean of 88 inches, and a standard deviation of 10 inches. What is the likelihood that the mean annual precipitation during 25 randomly picked years will be less than 90.8 inches?

7) A final exam in Statistics has a mean of 73 with a standard deviation of 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?

8) A mean score on a standardized test is 50 with a standard deviation of 10. Answer the following
a. What scores fall between -1 and +1 standard deviation?
b. What percent of all scores fall between -1 and +1 standard deviation?
c. What score falls at +2 standard deviations?
d. What percentage of scores falls between +1 and +2 standard deviations?

Purchase this Solution
Solution Summary

The solution gives detailed steps on solving a series of questions on standard normal distribution and empirical rule.

Purchase this Solution
Free BrainMass Quizzes
Measures of Central Tendency

This quiz evaluates the students understanding of the measures of central tendency seen in statistics. This quiz is specifically designed to incorporate the measures of central tendency as they relate to psychological research.

Measures of Central Tendency

Tests knowledge of the three main measures of central tendency, including some simple calculation questions.

Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

Know Your Statistical Concepts

Each question is a choice-summary multiple choice question that presents you with a statistical concept and then 4 numbered statements. You must decide which (if any) of the numbered statements is/are true as they relate to the statistical concept.

View More Free Quizzes
Related BrainMass Solutions

  • Empirical rule

    204303 Basis for Empirical Rule In this exercise, find the indicated area under the curve of the standard normal distribution, then convert it to a percentage and fill in the blank. The results form the basis for the empirical rule.

  • Standard Deviations of the Mean

    584943 Standard Deviations of the Mean Use the empirical rule of statistics to explain the percentage of data values in a normal distribution that fall within: a) 1 standard deviation of the mean b) 2 standard deviations of the mean c) 3 standard

  • Normal Distribution and Birth Weights

    The birth weights follow a normal distribution. 1. Label the number line so that the curve is a normal curve and follows the properties of the normal distribution. Include 3 standard deviations above and below the mean. 2.

  • Chebyshev's theorem and normal distribution

    124152 Chebyshev's theorem and normal distribution Given a normal distribution of data, we know from the Empirical Rule that in between 2 standard deviations from the mean (i.e. xbar - 2s..to..xbar + 2s) there lies about 95% of all the data.

  • Chebyshev's Theorem vs. Empirical Rule

    The Empirical Rule is a rule in statistics that says for a normal distribution, most of all of the data will land between three standardized yet different deviations from their mean.

  • MCQs: Empirical rule of Normal Distribution

    The solution provides answers to multiple choice questions on Empirical Rule of normal distribution. Relevant workings are also included.

  • Empirical Rule for Statistics Students

    The Empirical Rule also referred to as the Three Sigma Rule, or the 68-95-99.7 Rule, can be used to solve many problems that involve a normal distribution, where almost all data falls within three standard deviations of the mean.

  • The Empirical Rule For Statistics Students

    487403 The Empirical Rule For Statistics Students For a normal distribution curve with a mean of 19 and a standard deviation of 6, which range of the variable defines an area under the curve corresponding to a probability of approximately 99.7%?

  • What are the times that approximately 68.6% of all workers will fall?

    Empirical rule states that for a normal distribution, About 68% (precisely 68.27%) of the values lie within 1 standard deviation of the mean (or between the mean minus 1 times the standard deviation, and the mean plus 1 times the standard deviation

  • Statistics (The Empirical Rule vs. Chebyshev's Theorem)

    The Empirical Rule is a rule in statistics that says for a normal distribution, most of all of the data will land between three standardized, yet different, deviations from their mean.

View More Related Solutions