Suppose you would like to measure the probability that someone is admitted or not admitted on the basis of GRE score and GPA. In order to measure that probability you would conduct a logistic regression. A value of 1 will be given to students who are admitted and a value of 0 would be given to students who are not admitted. The dependent variable is binary and dichotomous. It will contain data of 0(not admitted) and 1(admitted). The independent variable will be GPA and GRE scores
This equation will go as follows: 
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logit(p)= b0+ B1*GRE+ B2*GPA.
The probability that a student is admitted would be P(y=1) = 1/(1+exp(-logit (p))