The ratio of hard and easy questions in an exercise is . How many hard questions does the exercise have if there are questions in all ?
Since ,the ratio of hard and easy questions in an exercise is .
Therefore, let the number of hard and easy questions be and respectively.
so, the total number of questions Hard questions + easy questions
Since ,the total number of questions
Therefore,
.
Therefore, total number of hard questions
Hence ,number of hard questions .