1. No, because the ratio 8:5 could be simplified from any factor of thirteen. 26 students in the class with 16 boys and 10 girls has the same ratio as 39 students in a class with 24 boys and 15 girls. So no, there is no accurate way to determine the number of students with the given information.
2. You can determine whether or not 2 ratios are equivalent if they can simplify to the same ratio. Using the first question as an example, 8:5 and 16:10 are the same ratio, because when you simplify the fraction 16/10, it is 8/5.
