If there are 90 students and the ratio of boys to girls is 3:2, that means 3x+2x=90
Combine like terms: 5x=90
x=18
2x (girls)=36
3x (boys)=54
1/3 of the boys scored full marks, so 54/3=18 boys scored full marks
The number of girls who scored full marks is half of the number who did not score full marks means that 1/3 of the girls scored full marks. 36/3=12, so 12 girls scored full marks.
(I don't know what the question is sorry if it's incorrect but there's not enough information)
When you a coin flips there are 2 possible outcomes which are either heads, or tailer, when you roll a die there are six outcomes, one to six. Putting these together means you have a total of 2×6=12 outcomes
