Purchase Solution

Normal Probability: Life span of bulbs & Cut off mark

Not what you're looking for?

Ask Custom Question

1). In an examination the mean score was 80, the standard deviation was 10, and the grades followed a normal distribution. The instructor wants to assign A's to the top 12%. Where should the cutoff point for A's be?

(2). A company manufactures electric light bulbs that have an average life of 1000 hours and a standard deviation of 50 hours. Find the probability that a bulb selected at random will have a life span of between 900 and 950 hours.

Purchase this Solution

Solution Summary

The solution provides step by step method for the calculation of probability using the Z score. Formula for the calculation and Interpretations of the results are also included. The life span of bulbs and cut off marks are examined.

Solution Preview

Please see the attachments.

Statistic
1). In an examination the mean score was 80, the standard deviation was 10, and the grades followed a normal distribution. The instructor wants to assign A's to the top 12%. Where should the cut off point for A's be?
Answer
Let x be the scores obtained in the examination. Given that X is normal with mean µ = 80 and standard ...

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.

Terms and Definitions for Statistics

This quiz covers basic terms and definitions of statistics.

Measures of Central Tendency

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

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.