Answer: A. 19kg B. 19 C. {(<19,>19), (<19, 19), (19, >19), (19,19)}
Step-by-step explanation: A. For this question, you have to add all of the numbers together and divide by the amount of data their is or the number of numbers given. In this case, 22+20+15+21+18+19+18 is 133 which then divided by the amount of numbers, which is 7, is 19. This would give the average weight, in kilograms, 19 kg. This is also known as the mean.
B. When a question is asking about median, you have to order the numbers least to greatest and find the one in the middle, in this case it is 15, 18, 18, 19, 20, 21, 22. So the median would be 19 as well. If given an odd number, you would have to fine the two middle numbers and find the average of those numbers.
C. I don't understand what this question is asking. If it is asking what should their weights be in order to keep the median of 19, one weight could be less then 19 and one could be greater, they could also both weigh 19kg to maintain the median of 19. Or one could be 19 while one is greater and one could be 19 while one is less than 19.