A test consists of 70 true or false questions. If the student guesses on each question, what is the standard deviation of the number of correct answers?Pl A test consists of 70 true or false questions. If the student guesses on each question, what is the standar?
Probablity of being true = p = 1/2
Probablity of being true = q = 1-p = 1- 1/2 = 1/2
variance = npq = 70 * (1/2) * (1/2) = 17.5
standard deviation = sqrt (17.5) = 4.18Pl A test consists of 70 true or false questions. If the student guesses on each question, what is the standar?
standard deviation = sqrt [np(1-p)] = sqrt( 70 x 0.5 x 0.5 ) = ..
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