Solution of problem N3709 probability theory total prob

Solution of problem N3709 probability theory total prob

3709. For the first typist, the probability of making a typo on the page is 0.03, and for the second, 0.12. The second one and a half times faster than the first. Printed pages are folded together. One page is taken at random. What is the probability that it contains a typo?

Additional information:

Detailed solution. Decorated in Microsoft Word 2003 (Quest decided to use the formula editor)