Question 11. In the morning, five friends had identical fully charged mobile phones. By the evening, Bob had spoken on the phone as much as Anne and Christina together. Bob ran out of power. David had not used his phone at all. Which phone belonged to Edward? Let's start off by saying that Bob ran out of power. So that will be 3, since that phone has no more battery. That is not Edward's phone. Then, we notice that David had not used his phone at all. That will be the battery with full charge. So that is option 1. That is not Edward's phone. Next, we take a look at our final piece of information. Bob spoke on the phone as much as Anne and Christina together. We know that Bob's phone is the battery with number 3. Then, we have to take a look at which two phone batteries would come together to look the same. If we look at phones 4 and 5, we see that they were used to be a total of 3. So, that leaves Edward's phone, which will be option B2.

mobile phones

battery usage

Edward's phone

phone puzzle

friends