20 mathematical questions were given to a student. For each correct question, the student was promised 10 chocolates. However, for every wrong question, it was decided that he would have to give back 5 chocolates.
To get a maximum number of chocolates, the student answered all the 20 questions. As a result, he got some answers wrong and got 125 chocolates at the end of the evaluation.
Can you calculate how many answers he gave were incorrect ?
Solution:
5 questions
Explanation:
This question can be solved using a simple trick. If all the questions were answered correctly, the student would have 200 chocolates.
For every wrong answer, he will lose 5 chocolates and he will also lose 10 chocolates that he would have gained if he would have answered correctly. Thus, for every wrong answer, you have to deduct 15 chocolates from 200.
200 - 125 = 75
15 * 5 = 75
Hence, he gave wrong answer for 5 questions.