Create a boosting ensemble classification tree model using the accompanying data set (predictor variables: x₁ to x₅; target: y). 

a. What are the overall accuracy rate, sensitivity, and specificity of the model on the validation data? 

b. What is the lift value of the leftmost bar of the decile-wise lift chart? 

c. Score a new record with the following values: x₁ = 52.8, x₂ = 230.50, x₃ = 1, x₄ = 144, x₅ = 6.23. How would the record be classified using the boosting ensemble tree model? What is the probability of the record belonging to Class 1?