The task is to generate the correct answer for a given math problem.

Q: Problem: the average weight of a group of boys is 30 kg . after a boy of weight 45 kg joins the group , the average weight of the group goes up by 1 kg . find the number of boys in the group originally ?

A: 14
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Q: Problem: at a certain fruit stand , the price of each apple is 40 cents and the price of each orange is 60 cents . mary selects a total of 30 apples and oranges from the fruit stand , and the average ( arithmetic mean ) price of the 30 pieces of fruit is 56 cents . how many oranges must mary put back so that the average price of the pieces of fruit that she keeps is 52 cents ?

A: 1
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Q: Problem: a train 100 m long crosses a platform 125 m long in 15 sec ; find the speed of the train ?

A:
61.2 kmph
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