The Grade Distribution for a Certain Class Is Shown in the Table

question 218

Short Answer

The grade distribution for a certain class is shown in the table. What is the probability that a student selected at random from this class received a passing grade (D or better)? Round to two decimal places, if necessary, and be sure to express answer in decimal form, not as a percentage.
The probability is __________.

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Definitions:

Weber's Law

A principle of perception that states the change in a stimulus that will be just noticeable is a constant ratio of the original stimulus.

Psychophysics

The scientific study of the relationship between physical stimuli and the sensations and perceptions they produce in the human mind.

Weber's Law

A principle that states the smallest change in a stimulus, such as weight or brightness, that can be detected is a constant proportion of the original stimulus's intensity.

Differential Threshold

The smallest detectable difference between two stimuli or the minimum change in intensity that a person can detect.