Our University prescribes Modern physics by Arthur Beiser for learning relativity. There are many tough(for me:shy:) problems in the book.I usually solve problems from other books tone such problem had the number 52. I had tried to solve it and it took me 2 hours to solve. I had to make many assumptions. To check whether my solutions and assmptions were right, I looked at the back of the book for answers. To my surprise, I found that even number problems' answers were not included and only odd problems' answers were present. :surprised . I got very much frustrated and threw the book.... Even numbered problems are much tougher and there were no solution for those...This just hinders learning according to me. To check whether my conceptual understanding was right, I need answers. When I work hard to solve and can't find the right guidance, it is frustrating. I don't know why even number problems' answers are not printed. Could someone explain me why?