A Bank Manager Is Interested in Assigning a Rating to the Holders

Short Answer

A bank manager is interested in assigning a rating to the holders of credit cards issued by her bank. The rating is based on the probability of defaulting on credit cards and is as follows. To estimate this probability, she decided to use the logit model,
P = , where
y = a binary response variable which is 1 if the credit card is in default and 0 otherwise
x₁ = the ratio of the credit card balance to the credit card limit (in %)
x₂ = the ratio of the total debt to the annual income (in %)
The following output is obtained. Note: The p-values of the corresponding tests are shown in parentheses below the estimated coefficients.
Assuming the debt ratio is 30%, what is the range of values for the balance ratio that yields the fair rating?