problems with percentages

In a problem with percentages, we always use a direct rule of three.

1. A magazine for teenagers sells 110.000 copies each month. The company president wants to increase the sales by 6%. How many extra magazines would they have to sell to reach this goal?

2. In 2008, a house cost 30.000€. A buyer gets a 10% discount. How much money does the house cost now?

  The house cost 27.000 €

3. Karen bought an antique vase for 120€. Two years later its value increases by 25%. What is the new value of the vase?

   The new value of the vase is 150 €

Exercises:

1.- I paid 480 € for a TV set that was 20% off that day. How much did it cost before the sale?

2.- 60 students play the piano in a musical school and they are 15% of the total of students. How many students are there in this school?

Solutions: 1) 600 €; 2) 400 students