



 
Hint: IF the two events "A" and "B" were independent this problems would be rather easy. But they aren't: if (A) is true then the third student's number is likely to be high, making (B) more likely. How can you rephrase this in terms of events that are independent? Specifically, which of the six students must have the highest roll number? And once this is given, what other easy and independent conditions give the desired event? Good Hunting!  


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