Here is a problem based on Statistics from Australian Mathematics Competition, 2014.
In a competition between four people, Sally scored twice as many points as Brian and 30 points more than Corrie. Donna scored 50 points more than Brian. Which of the following statements is definitely true?
But try the problem first...
Answer: Sally and Donna together scored more than Brian and Corrie.
Australian Mathematics Competition – Upper Primary Division - 2014 - UP 21
Statistics 10th Edition - Robert S. Witte and John S. Witte
For first hint we can use a table form with some possibilities :
So in the previous hint from the table its clear that the 1st , 2nd and 4th options are not correct. Now if we go with the higher numbers like 90,100 etc then there will be a change with the values.Try to find it out using a table.
I guess you have noticed the differences in values let try to do that......
So can understand from this table that the 3rd option is also not correct .
We are told that Sally scored 30 points more than Corrie and Donna scored 50 points more than Brian, and so together Sally and Donna always scored 80 points more than Corrie and Brian