If you still specifically want N.G. Das’s book without paying, here are the only ethical methods:
host digital copies, these are often user-uploaded documents and may not always be authorized by the publisher. Amazon.com Book Overview Ng Das Statistical Methods Volume 1 Pdf Free Download
Many professors keep a in the department office or library. Some departments have a “textbook bank” funded by alumni. Politely ask if you can borrow for a semester. If you still specifically want N