Grades 5-6 Video Solutions 2022-2022_5-6

Video Transcription

Question number 19. Lisa has four dogs. Each of the four dogs weighs an integer number of kilograms. No two of them weigh the same. Their total weight is 60 kilograms. The second  heaviest dog weighs 28 kilograms. How heavy is the third heaviest dog? So what do we know? We know that the second heaviest dog is 28 kilograms and the total  sum of the dogs weight is 60 kilograms. So the first heaviest dog really can only be slightly heavier than the second heaviest dog because 28 plus 29 is already 57. That's  already pretty close to our maximum of 60. And then that tells us in turn that the third and fourth dogs must both be super light. So the other thing we know is that dogs have  unique weights. And again, these are all integer values. So the minimum weight of the third and fourth dogs together has to be 1 plus 2 is 3 kilograms. Again, this corresponds  to what we're saying, that the third and fourth dogs must both be very light. In this scenario, the first dog would be 60 minus the weight of the second dog minus the weight of the  third and fourth dogs combined, which is 31 over here, to get us 29 kilograms. 29 kilograms is also the minimum weight for the first dog, so this is the only possible case. And  of course, that means that the third heaviest dog weighs 2 kilograms and the answer is A.

Video Summary

Summary Not Available