There are twice as many boys as there are girls if 30% of the boys and 45% of the girls failed in the exams then. What percentage of the class passed the exams?

65%

40%

52%

None of these

Let's say the number of girls is x. Then, the number of boys is 2x (since there are twice as many boys as girls).

Total students = x (girls) + 2x (boys) = 3x

Now, let's calculate the number of students who failed:

Girls who failed = 45% of x = 0.45x

Boys who failed = 30% of 2x = 0.6x

Total students who failed = 0.45x + 0.6x = 1.05x

Now, let's calculate the number of students who passed:

Total students who passed = Total students - Total students who failed

= 3x - 1.05x

= 1.95x

Percentage of students who passed = (1.95x / 3x) × 100%

= 65%