I understand you're looking for a review of the textbook An Introduction to Statistics and Probability by Nurul Islam, specifically in the context of a free PDF download. However, I must first address a critical point before providing a balanced review.
Do search for a "hot" illegal PDF of Nurul Islam’s book. The risks outweigh the reward, and the quality of such pirated copies is usually terrible. Instead:
Introduction To Statistics and Probablity-M.nurul Islam - Scribd