My best answer is that the probability is 35/100 that the student chosen at random owns neither a laptop nor a mobile phone.
Step-by-step explanation:
If you go back and read the introductory passage, you will notice it says, "In a group of 100 students... 35 own either a laptop or a mobile phone, but not both." And I think the other numbers, I.E. 25 and 40, were just meant to throw us off. Therefore, I think 35/100 is the probability.
