Probability

[Atria]

shouldn't the answer be (1-0.75)/0.45 = 0.5555 instead of 0.45/0.75 = 0.6 because we are trying to calculate the students that don't eat regularly in the cafeteria?

 

[Cubist]

shouldn't the answer be (1-0.75)/0.45 = 0.5555 instead of 0.45/0.75 = 0.6

I assume that you are talking about the answer to part b. The calculation that I made bold is wrong, even though it gives the correct result. I recommend that you make a Venn diagram, and then think about the area(s) that represent:-

• % of students who don't eat regularly in the cafe
• % of students who don't eat regularly in the cafe AND who also want longer opening hours